Question

What does the quadratic function

f(x) = x2 - 6x + 8 look like when it is
rewritten in the form f(x) = a(x − p)2 +q?

Answer 1

f(x) = (x -3)^2 - 1

Explanation:

f(x) = x^2 - 6x + 8

a = 1, b = -6 and c = 8

So we are finding half of the b equation (ignore the negative sign)

Half of 6 is 3, so we are going to square 3 (3^2 = 9) and add 9 to the left side and subtract 9 to the right side

(x) = (x^2 - 6x + 9) + (8 - 9)

You can tell the polynomial is a perfect square, so we will have to factor it using the perfect square method

(x^2 - 6x + 9)

square toot of x^2 is x and square root of 9 is 3 and the operation sign after the a number is a minus sign

(x -3)^2

Don't forget the rest of the equation from before

(x -3)^2 + (8 - 9)

(x -3)^2 - 1

So the equation is f(x) = (x -3)^2 - 1