Which polynomial is a perfect square trinomial?

9x2 − 12x + 4
36b2 − 24b + 16
16x2 − 24x − 9
4a2 − 10a − 25

Step-by-step explanation:

Eliminate the last two possible answers immediately, because their constants are negative.  A perfect square trinomial MUST have a positive constant.

If we factor the first answer choice, we get (3x - 2)(3x - 2) = 9x^2 - 12x + 4.  This is a perfect square trinomial.

Looking at the second answer choice:  (4x - 3)(4x - 3)  = 36b² - 24x + 9.  This is also a perfect square trinomial.

Please note:  Please use " ^ " to indicate exponentiation:

9x^2 is correct; 9x2 is incorrect.                                            

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