How do you solve the following system: 4x+3y= -1 , 4x-5y-23=0 ?

2 Answers
Aug 2, 2018

x=-5/32 and y = -1/8

Explanation:

The x terms are the same in both equations.

If you subtract the two equations the x terms will be eliminated.

color(white)(xxxxxxx) 4x+3y =-1" "...A
color(white)(xxxxxxx) 4x-5y =" "0" "...B

A-B:color(white)(xxxxxx)8y = -1
color(white)(xxxxxxxxxxxx)y = -1/8

color(white)(xxx) 4x +3(-1/8) = -1

color(white)(xxxxxxxx) 4x -3/8 = -1
color(white)(xxxxxxxxxxx) 4x = -1+3/8
color(white)(xxxxxxxxxxx) 4x = -5/8
color(white)(xxxxxxxxxxxx) x = -5/32

Check in B

4(-5/32) -5(-1/8)

-5/8 +5/8

=0

Aug 3, 2018

x=2 and y=-3

Explanation:

(4x+3y)-(4x-5y)=-1-23

8y=-24, so y=(-24)/8=-3

Hence,

4x+3*(-3)=-1

4x-9=-1

4x=8, thus x=8/4=2