Question

Which equation is an identity?

a. 8-(5x 2)=-5x-6

b. 7z 10-z=8z-2(z-5)

c. 8m-4=5m 8-m

d. 6y 5=6y-5

Answer 1

7z + 10 - z = 8z - 2(z - 5)
7z + 10 - z = 8z - 2z + 10
6z + 10 = 6z + 10
6z - 6z = 10 - 10
0 = 0

Therefore, 7z + 10 - z = 8z - 2(z - 5)