Question

PLEASE HELP PLEASE
what are the x-intercept(s) of the graph of y + 30= x^2 +2
??

Answer 1

xint is when y=0

Answer 2

y + 30= x^2 +2

0 + 30= x^2 +2

30= x^2 +2

Answer 3

And now solve for x

Answer 4

How!!

Answer 5

We start from here:
30=x^2+2
Now we substract 2 both sides.
What do we get?

Answer 6

Oh, 28= x^2

Answer 7

But nothing squares to 28

Answer 8

Great! And now we take the square root at both sides:
\[x=\pm \sqrt{28}\]

Answer 9

We can simplify a bit more using this: 28=4*7
Any idea?

Answer 10

Four times seven is 28

Answer 11

Factoring...? I'm confused

Answer 12

@rafabc02

Answer 13

Sorry, I'm back. a sec please

Answer 14

\[\sqrt{28}=\sqrt{4*7}=\sqrt{4}*\sqrt{7}\]
And then sqrt(4)=?

Answer 15

2??

Answer 16

Good! So we get this:
\[x=\pm 2*\sqrt{7}\]
There we have the two x intercepts:
\[x=2*\sqrt{7}\] and
\[x=-2*\sqrt{7}\]

Answer 17

Any doubt?

Answer 18

@jrosesweet
Was this useful?

Answer 19

@rafabc02 omg I wrote the question wrong

Answer 20

It's supposed to be y+30 = x^2 +x

Answer 21

Ok, no worries! We do the same: Plug x=0 and solve for y.

Answer 22

No sorry
Plug y=0 and solve for x

Answer 23

0+30=x^2+x
And now?

Answer 24

30=x^2+x

Answer 25

@rafabc02

Answer 26

now substrac 30 both sides

Answer 27

what did you get?

Answer 28

X^2+x-30....?

Answer 29

Idk

Answer 30

x^2+x-30=0
Remember the quadratic formula?
Take a look at the 3rd example:
http://tutorial.math.lamar.edu/Classes/Alg/SolveQuadraticEqnsII.aspx

Answer 31

Yeah

Answer 32

So put a b and c into the quadratic formula .

Answer 33

That's it! And which are the values for a, b and c?

Answer 34

A= 1 b=1 c=30

Answer 35

@rafabc02