Geometry: Logic and Reasoning

[Rachel Maddiee]

Solve -3(a+3) +5 (3-a) = -50

 

I can’t apply Properties of Equality.

[studiot]

1 hour ago, Rachel Maddiee said:

Solve -3(a+3) +5 (3-a) = -50

 

I can’t apply Properties of Equality.

 

Why not ?

I make a = 7

Edited September 12, 2019 by studiot

[Rachel Maddiee]

Can you show me ?

[Sensei]

First, you need to multiply what you have prior bracket with what is inside of bracket
e.g. -3(a+3) = -3*a-3*3 = -3a-9

then the same with second one,

5(3-a)=5*3-5a=15-5a

then move the all numbers to the right side, changing signs

-50+9-15=-56

sum the all a on the left side

-3a-5a=-8a

so you have finally

-8a=-56

divide by -8 either side

a=-56/(-8)=56/8=7

ps. It's not geometry, but algebra. Linear equation with single unknown.

https://www.khanacademy.org/math/cc-eighth-grade-math/cc-8th-solving-equations

 

Edited September 12, 2019 by Sensei