How do you solve 6x - 2y = -16 and 4x + 4y = -32 ?

2 Answers
Aug 10, 2016

x=-4
y=-4-

Explanation:

6x-2y=-16 and
4x+4y=-32
or
2x+2y=-16
or
x+y=-8
Adding up the equations 6x-2y=-16 and 2x+2y=-16
We get
6x-2y+2x+2y=-16-16
or
8x=-32
or
x=-32/8
or
x=-4--------------------Ans 1
By putting the value x=-4 in the equation x+y=-8
We get
-4+y=-8
or
y=4-8
or
y=-4-----------------------Ans 2

Aug 10, 2016

x = -4 and y = -4

Explanation:

Neither of the equations is in the simplest form. Let's do that first and see what we end up with.

6x-2y = -16 " "(div 2)" " rArr 3x-y =-8 ..........A

4x + 4y = -32 " " (div 4) " " rArr x+y =-8 ............B

We notice that +y and -y are additive inverses which will add to 0 if we add equations A and B together.

color(white)(................)3x-y =-8 ..........A
color(white)(.................)x+y =-8 ............B

A+B color(white)(.........) 4x = -16
color(white)(.....................)x = -4
color(white)(....................)y = -4