Question

Brianna is graphing the function f(x) = x2 + 6x + 5. What x-intercepts should Brianna use to graph f(x)?

–5 and –1
–5 and 1
–1 and 5
1 and 5

Answer 1

A. -5 and -1

Explanation:

Correct on edge 2021! :)

Answer 2

First choice.

Explanation:

The x-intercepts happen when y=0.

Just like the y-intercepts happen when x=0.

So anyways we are asked to find the x-intercepts.

So set y=0 (set f(x)=0):

0=x^2+6x+5

0=ax^2+bx+c

Since a=1, all we have to do is find two numbers that multiply to be 5 and add up to be 6.

Those numbers are 5 and 1 because 5(1)=5 and 5+1=6.

So the factored form of x^2+6x+5 is (x+5)(x+1).

The equation we have is:

0=(x+5)(x+1).

This means we have x+5=0 or x+1=0.

We need to solve both equations.

x+5=0

Subtract 5 on both sides:

x=-5

x+1=0

Subtract 1 on both sides:

x=-1

So the x-intercepts are at (-5,0) and (-1,0).

OR

Some people just say at -5 and -1.