Alaina was asked whether the following equation is an identity:
(20 + 1)2 – (2 + 1)2 = 3(x + 1)2 – 1
She performed the following steps:
(2x + 1)2 – (3+1)
Step 1
= 4x2 + 4x + 1-2? + 2x + 1
Step2
= 3.2? + 6x + 2
Step 3
= 3x2 + 6x + 3-1
Step 4
= 3(z? +22+1)-1
Step5
= 3(x + 1)2 – 1