Question

Which factorization is incorrect? 1) x3 + 5x2 + 4x + x2 + 5x + 4 = (x + 4)(x + 1)2 2) 4d3 – 4d2 – 9d + 9 = (d – 1)(2d – 3)2 3) 27h3 – 8k3 = (3h – 2k)(9h2 + 6hk + 4k2 ) 4) 64 – 9t2 = (8 + 3t)(8 – 3t)

Answer 1

The second option is the incorrect:

2) 4d3 – 4d2 – 9d + 9 = (d – 1)(2d – 3)^2

Explanation:

Let's check each one of the factorizations:

1) x3 + 5x2 + 4x + x2 + 5x + 4 = (x + 4)(x + 1)^2

(x + 4)(x + 1)^2 = (x + 4)(x2 + 2x + 1) = x3 + 6x2 + 9x + 4

x3 + 5x2 + 4x + x2 + 5x + 4 = x3 + 6x2 + 9x + 4

This one is correct.

2) 4d3 – 4d2 – 9d + 9 = (d – 1)(2d – 3)^2

(d – 1)(2d – 3)^2 = (d - 1)(4d2 - 12d + 9) = 4d3 - 16d2 + 21d - 9

4d3 – 4d2 – 9d + 9 = 4d3 - 16d2 + 21d - 9

This one is incorrect.

3) 27h3 – 8k3 = (3h – 2k)(9h2 + 6hk + 4k2 )

(3h – 2k)(9h2 + 6hk + 4k2 ) = 27h3 - 8k3

This one is correct.

4) 64 – 9t2 = (8 + 3t)(8 – 3t)

(8 + 3t)(8 – 3t) = 64 - 9t2

This one is correct.

So the incorrect option is the second one.