Question

Which expression is not a perfect square trinomial?

Answer 1

Answer:

Remember that a perfect square trinomial can be factored into the form (a+b)^2

or (a-b)^2

Examples:

(x+2)(x+2) is a perfect sq trinomial --> x^2+4x+4

(x-3)(x-3) is a perfect sq trinomial --> x^2-6x+9

(x+2)(x-3) is not a perfect square trinomial because its not in the form (a+b)^2 or (a-b)^2

Now to answer your question,

for the first one, x^2-16x-64, you cannot factor it so it is not a perfect square trinomial

for the second one, 4x^2 + 12x + 9, you can factor that into (2x+3)(2x+3) = (2x+3)^2 so this is a perfect square trinomial

for the third one, x^2+20x+100 can be factored into (x+10)(x+10) so this is also a perfect square trinomial

for the fourth one, x^2+4x+16 cannot be factored so this is not a perfect square trinomial

Therefore, your answer is choices 2 and 3

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Step-by-step explanation:

Answer 2

Answer:

A. 121 plus 11 y plus y squared; $121+11y+y^2$

Step-by-step explanation:

We are asked to choose the expression that is not a perfect square trinomial.

We know that a perfect square trinomial is in form $a^2\pm 2ab+b^2$.

A. 121 plus 11 y plus y squared

$121+11y+y^2$

$11^2+11y+y^2$

For this expression to be a perfect square trianomal, the middle term needs to be $2*11y=22y$. Since the middle term is not equal to $2ab$, therefore, option A is not a perfect square trinomial.

B. 100 minus 20 y plus y squared

$100-20y+y^2$

$10^2+2*10y+y^2$

Therefore, option B is a perfect square trinomial.

C. 81 plus 18 y plus y squared

$81+18y+y^2$

$9^2+2*9y+y^2$

Therefore, option C is a perfect square trinomial.

D. 144 plus 24 y plus y squared

$144+24y+y^2$

$12^2+2*12y+y^2$

Therefore, option D is a perfect square trinomial.