How do I find the x-intercepts for this equation?

Question

f(x)= -x²+11x-28

I know I'm supposed to solve for

-x²+11x-28=0

But I'm stuck at

-x²+11x=28

What am I supposed to do after that?

Answer 1

x ² - 11x + 28 = 0
(x - 7) (x - 4) = 0
x = 7 , x = 4

Answer 2

rearrange the equation -x^2 + 11x = 28 by adding -28 to each side...

-x^2 + 11x - 28 = 0
(-x + 7)(x - 4) = 0
now this is true if either
-x + 7 = 0
or
x - 4 = 0
x = 7 and x = 4 are the x intercepts

Answer 3

The easier way for this one would be to factor it. I assume you know how to factor equations like this.

f(x)= -(x²-11x+28)
Two numbers that multiply to 28, and add to -11 are -4, and -7, so
f(x)= -(x - 4)(x - 7)
X intercepts are on the x axis, and on the x axis y = 0.
0 = -(x - 4)(x - 7)
Solving this we find the intercepts to be 4 and 7.
You can check them by replacing them with x in the equation. It should then = 0.

Answer 4

Your not solving it correctly. You need to factor.
-x^2 + 11x - 28
(-x + 4) (x - 7)
so x=4, 7

Answer 5

back up a step

-x²+11x-28=0
(-x - )(x+ )
find the factors of 28 that comine to give you 11, 7 and four
(-x-7)(x+4)
-x-7=0
-x=7
x=-7

x+4=0
x=-4

Answer 6

after you have -x²+11x-28=0 multiply by -1
x²-11x+28=0
Then factor
(x-4)(x-7)=0
x=4
or x=7
so it intercepts the x axis at 4 and 7

Answer 7

first set it equal to zero by putting everything on the other side of the zero so you get x^2-11x+28=0that makes the equation ALOT "nicer" then think to yourself, what two numbers add to the middle term and multiply to the last term. Hint, one of them is 7...

Then "foil" to check yo self!

Answer 8

f(x) = -x² + 11x - 28
f(x) = x² - 11x + 28
(x - 4) (x - 7)

x = 4, 7