Which equation is an identity?
a.i (x+i)=xi - 1
b. i(x-2i) = xi - 2
c. (4x-7)(4x+1)= 15
d. (3x + (3x +21) = 7x +91 ​


Answer :

Answer:

D

Step-by-step explanation:

A and B are not, and C doesnt work so D