Question

Consider the function f(x) = x2 + 2x – 15. What are the x-intercepts of the function

Answer 1

Answer:

f(x)=4x-15

Step-by-step explanation:

Answer 2

f(x)=x^{2} +2x-15

we know that

The x-intercept is the value of x when the value of the function is equal to zero

so

in this problem

Find the roots of the function

equate the function to zero

x^{2} +2x-15=0

Group terms that contain the same variable, and move the constant to the opposite side of the equation

x^{2} +2x=15

Complete the square. Remember to balance the equation by adding the same constants to each side

x^{2} +2x+1=15+1

x^{2} +2x+1=16

Rewrite as perfect squares

(x+1)^{2}=16

Square root both sides

(x+1)=(+/-)\sqrt{16}

(x+1)=(+/-)4

x=-1(+/-)4

x1=-1+4=3

x2=-1-4=-5

x^{2} +2x-15=(x-3)(x+5)

therefore

the answer is

the x-intercepts are the points (3,0) and (-5,0)

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