Question

Which of the following is not a perfect square trinomial?

Answer 1

perfect square trinomials are in the form of: a^2 + 2ab + b^2

Answer 2

change the 1st term on each choice to the SQUARED version of it
then factor the middle term by 2, then recheck the choices

Answer 3

What do you mean by factor the middle term by 2 ?

Answer 4

\(\begin{array}{llll}
144+12y+y^2\implies &12^2+2(6)y+y^2\\
100+20y+y^2\implies &10^2+2(5)y+y^2\\
64-16y+y^2\implies &8^2-2(8)y+y^2\\
25+10y+y^2\implies &5^2+2(5)y+y^2
\end{array}\)

so... which one do you think?

Answer 5

like so

Answer 6

so like for 100 + 20y + y^2
100 = 10^2
so the middle should consist of 2*10*y = 20y
therefore option B IS a perfect square trinomial

Answer 7

hm... I got the ... olemme fix that

Answer 8

\(\begin{array}{llll}
144+12y+y^2\implies &12^2+2(6)y+y^2\\
100+20y+y^2\implies &10^2+2(10)y+y^2\\
64-16y+y^2\implies &8^2-2(8)y+y^2\\
25+10y+y^2\implies &5^2+2(5)y+y^2
\end{array}\)


there, now recheck the choices... what do you think?

Answer 9

I have to look for an error right ?

Answer 10

yep :) one that did not fit into the pattern of a^2 + 2ab + b^2

Answer 11

hmm... recall, as jigglypuff314 already pointed out, the middle term in a perfect square trinomial, is the multiplication of 2 * 1st term (non-squared), * 2nd term (non-squared)

Answer 12

Is it D ?

Answer 13

\(\bf (a+b)^2\implies a^2+2ab+b^2\qquad \qquad (a-b)^2\implies a^2-2ab+b^2\)

Answer 14

well, let's see D closely \(\huge 25+10y+y^2\implies 5^2+2(5)y+y^2\) is it not a perfect square trinomial?

Answer 15

It is !?

Answer 16

So the answer is C then....

Answer 17

\(\large 25+10y+y^2\implies \color{red}{5}^2+2(\color{red}{5})\color{red}{y}+\color{red}{y}^2\)

Answer 18

if you grab the 1st term, non-squared and 2nd term, non-squared, it should give you the middle term if multiplied by 2

Answer 19

I think I got it now, its A right ?

Answer 20

correct :)

Answer 21

Thank you soooooo much guys !!

Answer 22

yw