Which identity resulted from the proof in part a, which showed that a triangle with side lengths x2 − 1, 2x, and x2 + 1 is a right triangle?

we know that

In a right triangle

Applying the Pythagorean Theorem

In this problem

Let

substitute in the formula above

------> is ok

that means that is a right triangle

correct

step-by-step explanation:

option 3 . (5x + 1) - (-10x + 6)

step-by-step explanation:

option 1 :

(4x + 3) + (-9x + 4)

or 4x+3 -9x + 4

or -5x + 7

option 2

(x - 2) - (6x - 9)

or x-2-6x + 9

or -5x + 7

option 3

(5x+ + 6)

or 5x + 1 + 10x -6

or 15x -5

option 4

-4x+2x+7-3x

-7x + 2x + 7

-5x + 7

hence only option 3 did   not satisfy the given simplify expression.