Question

Determine which polynomial is a perfect square trinomial. Explain your answer.

Group of answer choices
A. 49x2 − 28x + 16
B. 9a2 − 30a + 25
C. 25b2 − 45b − 81
D. 16x2 − 24x − 9

Answer 1

The answer is B. 9a2-30a+25

Explanation:

First of all, the second sign is going to be +, so you can toss out C and D without checking.

Then you take the square root of the two ends, multiply them, multiply by two and see if it matches.

sqrt(49) * sqrt(16) = 7 * 4 = 28

28 * 2 = 56

56 <> 28

So toss A.

sqrt(9) * sqrt(25) = 3 * 5 = 15

15 * 2 = 30

So the answer is B

(3a - 5)^2 = 9a^2 - 30a + 25

By the way, use ^ to indicate an exponent.