Vastor

don't know how many years already I had my sinus infection, when I'm 12 years old already as much as I remember, 17 now, and still has it until today, does this disease can't be cured at all? I mean, I'm tired of this already, especially when it caused me having flu or cold like once / twice a month! >.< so, If I'm having flu I'm taking pills, make it gone, and I don't need to sneeze every 5 minutes or having my nose look like "cave's leak" are there any side affect of taking this pills regularly just to remove my flu "temporary"?(well, this pills will lose it protection ability after several day) p.s. if I put this on wrong forum, mind to move it

so, it's just basically the direct reasoning "from words to mathematic"?! usually, with equation, there always a way to derive, but this not really works with range it seems... btw, what a silly revision book, lucky I'm form 5 already,(revised what I learn from form 4 chapter for sake of proficiency) it's kind of lame to include chapter 2 into this chapter, especially when the reader is form 4, and with a confusing word problem (there is exercise tell "find the value of x which is mapped onto itself" wtf?!) good revision book for one who good at math, but not really for freshman. anyway, thnx to this book, I search on how to solve absolute value equation yesterday, which come out in exam today

with my high-school algebra style(plug and solve), I can't really perform any formula for this... but from what I understand, doesn't the exercise mean by "no solution" that [math]b^2 - 4ac < 0 [/math] ??? ok, got it, thnx, but... when I got here [math]k^2 + 2k -15 < 0[/math] [math](k-3)(k+5) < 0[/math] [math](k-3) < 0[/math] & [math](k+5) < 0[/math] [math]k < 3[/math] & [math]k < -5[/math] but the answer -5 < k < 3 I always "cheat" just to fit it into the answer [math](k-3)(-k-5) < 0[/math] [math](k-3) < 0[/math] [math]k < 3[/math] & [math](-k-5) < 0[/math] [math]-k < 5[/math] [math]k > -5[/math]

huh? x actually not equal 1 and for that reason it's real, why should I assume it anymore? I'm missing your point...

too much calculus for a "chapter 1: function"? xD oh, btw, this coming from exercise book, answer : -5 < k < 3 1. shape, *calculate on graph calculator*, herm, some sort of "reciprocal" 2. yeah, it's undefined, before = y reaching infinity, after = y moving from the infinity, the timeline of "after" and "before" is based on "x" 3. not really learned calculus deep enough to conclude anything here...

word problem? probably... k, let see function f is defined by [math]f(x) = \frac{kx - 4}{x - 1}, x \neq 1 [/math] find the range of values of k such that [math]f(x) = x [/math] has no solutions my trials, none, lol... anyone can give idea what this question mean by "solution" ?

thnx for the tips

hey guys, as a SPM candidate(GCE O-level equivalent), the exam considered to be not too hard and give me much free time. (currently doing good grade too) Thus, I can study(for fun) math. I don't know which order should I start, I mean looking in math playlist on Khan Academy... There:- - Arithmetic (mastered) - Developmental math - Pre-algebra(currently here) - Algebra - Geometry - Trigonometry - Probability - Statistics - Pre-Calculus - Calculus - Differential Equations - Linear Algebra - Vi Hart hope anyone can give right order for this, I mean of course the playlist before needed for the next playlist... etc.. p.s. study this because seems to be most of the lesson it give help a lot in exam syllabus too... even over the syllabus, it can give so much understanding and most importantly it is fun...

k, thnx

. "button error" hey guys. as we know that [math]x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} [/math] where the discriminant is [math] {b^2 - 4ac} [/math] and I thought discriminant is taken from the quadratic formula, which squaroot the result of discrimination. So, that's mean when discriminant's result is negative, the answer is not available. Yet, I want to explore more about the 'un-available root', I use calculator to calculate the equation that its discriminant is negative. Then, it bugging my mind somehow the x is founded! [math] x^2 - 3x + 4 = 0 [/math] [math] D = -7 < 0 [/math] [math] x = 1.5. [/math] did I miss anything here?

lmao, talking about basic, this is hardly possible in a formal high-school education which intuitive and imagination is forgotten, thanks to the ministry of education, they just give a bunch of formula and told us plugin the numbers (i don't know what is in their brain, khan academy teach much better) long story short, they just give me the variance formula as follow [math] \sigma^2 = \frac{\sum x^2}{frequency} - mean^2 [/math] and i don't have a clue of what u write... can u elaborate more, or give link so that i can get this thing into my brain? P.S. talking about gaining intuitive, i think i'm the only student in my classroom that can find median of a grouped number without using the given formula, and yes others just memorize the formula and plug-in the number (there nothing to be proud about, such simple intuitive can be gain easily, i'm in a top class anyway, shame to the text book )

[math] ax^2 + bx + c = 0 [/math] is general form by using factorisation, we can turn it into this form let's say... [math] (x - r_1)(x + r_2) = 0 [/math] then we get the roots as follow [math] x - r_1 = 0 [/math] [math] x = r_1 [/math] & [math] x + r_2 = 0 [/math] [math] x = - r_2 [/math] compare to forming an equation out of roots(where roots are given) it's different story, where it's giving me some headache to think about... usually, teacher will give formula [math] x^2 - (S.O.R) + (P.O.R) [/math] S.O.R = sum of root P.O.R = product of root but, I personally don't like remembering and plugin stuff in math, because that's not the way to learn it... so, I use this equation instead... [math] (x - r_1)(x + r_2) = 0 [/math] (an equation that i got from factorisation) and this is the part where my math got stuck... let's say it's given roots x = 3 and x = -2 so, i move on and turn x = 3 x - 3 = 0 but what does 0's value refer to?(i know it's y / f(x) but how does to proof that mathematically?) so, trying to not break any math law, i write on my answer paper this instead let y = 0 (because it's roots, so, its plot should be on the x intercept where y = 0) x = 3 + y x - 3 = y x - 3 = 0 and, x + 2 = 0 another question is, what calculation u can proof that "(x - 3)(x + 2) = 0" can be form from "x - 3 = 0" and "x + 2 = 0" ? i found this is so blurry, i know how to solve this all, but just don't get what math were used in this calculation, hope anyone can help...

based on the example 2 in this website why does the normal equation doesn't perpendicular to the tangent? or i do any calculation wrong?

The mean and standard deviation of 7 numbers are 5 and 3 respectively. Calculate a) solved b) the new value of the variance if every number is multiplied by 2 and then 5 is added to it. my attempt : [math] \sum x = sum-of-numbers [/math] [math] 5 = \frac{\sum x}{7} [/math] [math] {\sum x} = 35 [/math] so, multiply 2 and add 5 [math] 35(2) + 5 = 75 [/math] [math] {\sum x} = 75 [/math] find mean, [math] \frac{75}{8} = 9.375 [/math] [math] \sigma^2 = \frac{\sum x^2}{frequency} - mean^2 [/math] [math] \sigma^2 = \frac{75^2}{8} - 9.375^2 [/math] [math] \sigma^2 \approx 615.2344[/math] where the answer is [math] \sigma^2 = 36 [/math] seems to be i'm not good to use variance yet :/

ignore my last post, i'm not so good in algebra that time, anyway.. the discriminant seems to be derived from the quadratic formula, and quadratic formula is derived from general form of quadratic equation by moving the 'x' to LHS and others to RHS so, if the degree of 'x' is different (more than 2, etc), does the discriminant for the equation is different??? does it's needed for 'full' equation for each degree of polynomial function to be derived to get the discriminant? such as [math]ax^2 + bx + c[/math] for second degree [math]ax^3 + bx2 + cx + d[/math] for third degree etc or wait, did I'm being ridiculous now?

i answer second question, bcoz i don't know first question trial and error not suitable for this [math]4^x = 1/32 [/math] instead, simplify to make it easy to see [math]4^x = 32^{-1} [/math] [math]2^{2(x)} = 2^{5(-1)} [/math] [math]2x = -5[/math] [math]x = \frac{-5}{2}[/math] for uniq symbol in forum.. LaTex

actually, the thing that I worried about is the value, however, when i see again in the mathematica, the value is same.. hmm... after do some random calculation... i think i found the 'secret' behind this, thnx anyway ^^

I'm trying to solve this function. [math] = \frac{1 + (\frac {2x + 3}{3x- 4})}{(\frac {4x + 6}{3x-4}) - 3} [/math] [math] = \frac{\frac {2x + 3 + 3x -4}{3x- 4}}{\frac {4x + 6 - 9x +12}{3x-4}} [/math] [math] = \frac {5x - 1}{3x- 4} / \frac {-5x + 18}{3x-4}[/math] [math] = \frac {5x - 1}{3x- 4} * \frac {3x-4}{-5x + 18}[/math] [math] = \frac {5x - 1}{1} * \frac {1}{-5x + 18}[/math] [math] = \frac {5x - 1}{-5x + 18}[/math] but how come mathematica got this? mathematica 1 mathematica 2 where does the " -1 " came from???

there are 3 'main' branch of science :- physic biology chemistry for cosmology, I'm not sure but physic surely included. which mean that you should concentrated for physic more.. and before going to physic, you should learning mathematics until... algebra! and, good luck ^^

from your word, I assume u know arithmetic, so, i prefer u to start from pre-algebra, becoz arithmetic is for 6y.o. or so, which rare to see with such good vocab

and... what branches of science u interested for???

i think this is a good launcher.. http://www.coolmath.com/ http://www.youtube.com/user/khanacademy start from algebra, if not possible start from pre-algebra, if not then, take arithmetic

at 6:17, the equation should be [math]\Delta v = v_f - v_i[/math] but the vid shown that it substitute [math] v_y [/math] into the equation [math]\Delta v = v_f - v_y[/math] which would result in [math]\Delta v = v_f - \frac{1}{2}v_i[/math] does I miss something here? or Khan just do another mistake?

yes, and yes. anything that result the y = 0, like (5, 0) is x-intercept...

yes and yes