Question

Help please thanks

Which trinomials are perfect square trinomials?

Select each correct answer.

a2+15a+75

a2+26a+169

a2+14a+49

a2+4a+16

Which expressions are differences of squares?

Select each correct answer.

t2−4

h2−20

x2−169

a2+1

Answer 1

t^2 - 4 and x^2 - 169 are the right answers, just took the test.

Answer 2

Answer: Perfect squares are the middle two. Difference of squares are t^2 -4 and x^2 - 169

First, to be a perfect square the last term must be a perfect square number. Only 169, 49 and 16 are perfect squares. Second, the middle term must be twice the square root of the last term.

You can check this by using foil on the following expression:
(x + 13)(x + 13) You will get x^2 + 26x + 169 which is one of the perfect square trinomials.

For the difference of squares, you must be using subtraction and have two perfect squares.