Question

How do you find the x-intercept of f(x)=x^2-7 and f(x)=(x+4)^2-3?

Answer 1

the x-intercept is when y=0 so you need to set each equation equal to 0 and solve.

Answer 2

Do you know how to do this?

Answer 3

do i just solve for x or do i need to use the quadratic formula?? but is that possible since there's no b

Answer 4

Lets work through it. Take the left equation first. If you set it equal to 0 and solve for x we get to \[7=x ^{2}\]

Answer 5

okay then do i square root the 7?

Answer 6

from here we can say that \[x=\pm \sqrt{7}\] because when a negative is squared it becomes a positive, so there are two answers for the first equation. write this in coordinate form.

Answer 7

okay then. then it's the same for the other function too?

Answer 8

its a little trickier but ya. set it equal to zero and start to solve for x. you will have to add 3 to each side then expand the paranthesis

Answer 9

nevermind about expanding that will make it more complicated

Answer 10

oh okay then. should i expand the parentheses first then add 3 to both side??

Answer 11

haha oh okay then then just add 3, square toot it, then - 4?

Answer 12

hold on. I graphed it now I need to prove it arithmatically

Answer 13

haha now im confused

Answer 14

there needs to be 2 answers . x = -2.268, -5.732 by calculator. I'm sorry this one has me stumped about solving it by hand,

Answer 15

the first is correct

Answer 16

haha i actually have the answer in the back of the book but i dont get how to do it

Answer 17

I think you can say x+4 needs to equal the sqrare root of 3

Answer 18

@ChmE is right.

Answer 19

and solve it for x+3 = - square root of 3.

Answer 20

ahh scary perso here >.>.....

Answer 21

this should give you both of your answers

Answer 22

you suppose to set the y to zero and solve for the x. haha whatever @Cookiencreams17 and he best way to do it is reverse pemdas.

Answer 23

you have to solve for both positive and negative because when it is squared it wont matter. This is the correct method.

Answer 24

yep it's correct but the're 2 points

Answer 25

oh cool okay i got it thanks for the help

Answer 26

Ya, That one tripped me up for a bit. lol. welcome

Answer 27

if \[3=(x+4)^{2}\]then we can say \[+\sqrt{3}=x+4\]and\[-\sqrt{3}=x+4\]because when you take the square of each we arrive back at the original equation. If you solve for both of these equations you should get the 2 answers for x

Answer 28

Does that help?

Answer 29

yea it heps a lot thank you again. oh i was wondering how you do the square root thing haha i think it's cool

Answer 30

what thing?

Answer 31

the square root symbol

Answer 32

oh, click on the equation button below this text box. you can do all sorts of things

Answer 33

oh thats cool