Question

find the integral value of k that makes 4x^2+4x-k a perfect square trinomial, and express the result in factored form.

Answer 1

@campbell_st

Answer 2

ok... so this uses the discriminant.

For a perfect square the discriminant is equal to zero.

so you would substitute a = 4, b = 4 and k

then solve for k.

does that make sense..?

Answer 3

would it be 4x^2+4x? if not then it doesn't make sense to me

Answer 4

ok... do you know what the discriminant is?

its used to determine the type of roots that a quadratic will have..

Answer 5

so that will be what0?

Answer 6

if we square 4 we get 2

Answer 7

i mean root will be 16

Answer 8

well start with the basics.

the discriminant comes for the general quadratic formula and is

\[\Delta = b^2 - 4ac\]

you need a perfect square so \[\Delta = 0..... or...... 0 = b^2 - 4ac\]

in your problem you have a = 4, b = 4 and c = -k

you need to substitute and solve for k.

Answer 9

0=b^2-16-k so far

Answer 10

k=b^2-16

Answer 11

not quite its

\[0 = 4^2 - 4 \times 4 \times (-k)....... or..... 0 = 16 + 16k\]

Answer 12

i get k=-1

Answer 13

this correct?

Answer 14

thats what I get... which doesn't make a lot of sense as the quadratic isn't a perfect square with k = -1

Answer 15

oalright thanks for the help

Answer 16

glad to help...