Question

Use substitution method to solve the linear system.

Can someone please check if I did this problem right? Thanks

X+y=12
X+3/2y=3/2

Y=21
x=-9

Answer 1

To check, all you have to do is to see if your solution satisfies both equations.
Your solution satisfies the first, but not the second, so there is an erro

from the first: y = 12-x
first I would multiply the second by 2 to get rid of fractions
2x + 3y = 3
now sub in the first
2x + 3(12-x) = 3
2x + 36 - 3x = 3
-x = -33
x = 33
then y = 12-33 = -21

<b>x = 33 , y = -21</b>

check:
in first:
LS = x+y = 33-21 = 12 = RS
the 2nd:
LS = x + (3/2)y = 33 + (3/2)(-21)
= 33 - 31.5 = 1.5 = 3/2 = RS