Question

Which polynomial is a perfect square trinomial?

49x2 − 28x + 16

4a2 − 20a + 25

25b2 − 20b − 16

16x2 − 24x − 9

Answer 1

you have to complete (if possible) the squares!
or take the square roots of the extremes multiply them and then double what you get, for the expression to be a perfect square what u get should be equal to the middle term

Answer 2

for instance in the first option
\[ \sqrt{49x^2}=7x \]
\[ \sqrt{16}=4 \]
then
\[ 2(4)(7x)=56x \]

Answer 3

lol - thats what helper said!

Answer 4

plus when you expand this
\[ (a-b)^2=a^2-2ab+b^2 \]
the last term if ALWAYS positive. so which ones would you disscard inmediately?