Question

3x-2y=9 and y=2x-7 solve each system of linear equations by substitution. step by step please.

Answer 1

You first plug in y to the equation so you plug in 2x -7 to y so it would be 3x -2(2x -7) = 9 so you distribute/ multiply . So your new equation should be 3x -4x + 14 (by the way you get the positive 14 from -2 and -7 cause 2 negatives equals a positive.) after that you get rid of the variable so you subtract -4x + 3x which equals -x or to make it easier -1x and since x is by itself you don't need to cancel or divide anything out so your answer would just be 14 . Hope this helped !!!

Answer 2

y = 2x - 7....so sub in 2x - 7 for y in the other equation

3x - 2y = 9
3x - 2(2x - 7) = 9....distribute thru the parenthesis
3x - 4x + 14 = 9.....subtract 14 from both sides
3x - 4x = 9 - 14...simplify
-x = - 5...multiply by -1 to make x positive
x = 5

now sub 5 in for x in either of ur original equations to find y

y = 2x - 7
y = 2(5) - 7
y = 10 - 7
y = 3

now we can check our answers...(5,3)

3x - 2y = 9
3(5) - 2(3) = 9
15 - 6 = 9
9 = 9 (correct)

so ur solution is : (5,3) <==