Question

If x² + 8x +c is a perfect square trinomial, what is the value of c?

a. 32
b. 8
c. 16
d. 4
_______________________________

Find the values for x in the following equation:
x² + 4x -32 = 0

a. -8 & 4
b. 8 & -4
c. 8 & 4
d. 0, -8, & 4
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Find the x-intercepts for the following equation:
y = 6x² - 7x - 3

a. (3/2,0) & (-1/3,0)
b. (3,0) & (-1,0)
c. (7,0) & (12,0)
d. (-3/2,0) & (1/3,0)
______________________________

Find the values of y for the following equation:
2y² - 5y + 2 = 5

a. y = 1/2 & -3
b. y = 1/2 & 2
c. y = -1/2 & -2
d. y = -1/2 & 3

Answer 1

Okay @Ranya99, you're going to have to do some of the work here. We're here to help, not just do your homework for you. What are you stuck on? Answer these questions please:

1) What is a perfect square trinomial?
2) How do we find x intercepts of functions?

Answer 2

yeah I don't just need answers, I need to understand them too. Both acually.

Answer 3

Okay no problem, just in future try to say what it is you want rather than just post questions and you'll be able to get the best help. Can you answer my previous questions? If you don't know the answers, it's quite easy to look up :)

Answer 4

a perfect square is a number that can be expressed as the product of two equal integers

to find x-intercept, plug in 0 for y and solve for x

Answer 5

Exactly, so for 1 we want to find an a such that \[(x+a)^2=x^2+8x+c\]It would normally be something of the form (ax+b)^2 but we know the a in that case would be 1 so we can ignore it.
\[(a+x)^2=x^2+2ax+a^2=x^2+8x+c\]
We know 2a=8 and a^2=c. What are a and c?

Answer 6

Meant to write (x+a)^2 not (a+x)^2 - I know they're the same, it's just confusing.

Answer 7

I'm confused

Answer 8

Okay so as you said, a perfect square trinomial is the square of two products. (ax+b)^2. When we expand this, we get\[a^2x^2+2abx+b^2\]Setting this equal to your equation gives us\[a^2x^2+2abx+b^2=x^2+8x+c\]Now we equate coefficients to solve this. In front of the x^2, we have a^2 on the left and 1 on the right. So a^2=1 therefore a=1 (this is the step I skipped before).

In front of x, we have 2ab on the left and 8 on the right. We know a=1 from before, so our equation is 2b=8, so b=4.

Now we're left with b^2=c, and we just found b=4 so c=4^2=16.

This gives us:

\[(x+4)^2=x^2+8x+16\]

Does that explain it?

Answer 9

yeah

Answer 10

The second question doesn't really make sense to me, is that exactly how you see it?

Answer 11

yes

Answer 12

Ill call a haxor to help out with this.

Answer 13

@FlappyFlapper

Answer 14

Yes?

Answer 15

Yes

Answer 16

Yes, I guess

Answer 17

Yes I guess, what a Mess

Answer 18

We will both say what at the same time: 3, 2, 1

Answer 19

Oh sorry, I'm being thick. How do you solve:\[x^2 + 4x -32 = 0
\]

Answer 20

What

Answer 21

Yes I guess, a dress that's a mess.

Answer 22

With a bess to obsess

Answer 23

@tom982 I solved this one, it's -8 & 4

Answer 24

Correct. Now for 3 it's the same, just set y=0 and solve for x. For 4, we rearrange to make it equal 0 then solve like we did in 2 and 3.

Answer 25

@tom982 alright, got it
thanks a lot

Answer 26

No problem, happy to help.