Question

Zoe shows her work in finding the solution to 9 – 7x = 7 – 4(2x 3). which choice describes the error in her solution?

Answer 1

I'll assume the above equation is: 9 - 7x = 7 - 4(2x+3)

* do distributive multiplication
9 - 7x = 7 - 8x - 12

*move like terms
-7x + 8x = 7 - 12 - 9

* solve for x
x = 7 - 21
x = -14

To check, substitute x by its value -14

9 - 7x = 7 - 4(2x+3)
9 - 7(-14) = 7 -4[2(-14) + 3]
9 + 98 = 7 - 4(-28 +3)
107 = 7 - 4(-25)
107 = 7 + 100
107 = 107