Which polynomial is a perfect square trinomial?

36x^2 − 18x − 9

4a^2 − 28a − 49

25b^2 − 40b + 16

4x^2 − 6x + 9

Question

Which polynomial is a perfect square trinomial?

36x^2 − 18x − 9

4a^2 − 28a − 49

25b^2 − 40b + 16

4x^2 − 6x + 9

amistre64 · Answer

id bet 3 or 4

myininaya · Answer

$$(6x-3)^2=36x^2-2(6)(3)x+9 $$
$$(2a-7)^2=4a^2-2(2)(7)+49$$
$$(5b-4)^2=25b^2-2(5)(4)+16$$
$$(2x-3)^2=4x^2-2(2)(3)+9$$

amistre64 · Answer

ohohohoh..... discriminate of zero lol

myininaya · Answer

-2(2)(3) is not -6 
so whats left?
i give you a hint look at choice 3

amistre64 · Answer

25b^2 − 40b + 16

40^2 -4(25)(16)

1600 -100(16)

1600 -1600 = 0

amistre64 · Answer

.... also?  ;)

amistre64 · Answer

i figured it needed a + on the rearend

amistre64 · Answer

and 4 just looked rather weak and pathetic

myininaya · Answer

yes it does

anonymous · Answer

What are the factors of 3x^2 + 10x + 8?