How do you find the zeros, real and imaginary, of y=(x-3)^2+41 using the quadratic formula?

1 Answer
Dec 13, 2017

x=3+sqrt(41)i,3-sqrt(41)i

Explanation:

Given:

y=(x-3)^2+41

Expand (x-3)^2.

y=x^2-6x+9+41

Simplify.

y=x^2-6x+50 is a quadratic equation in standard form:

y=ax^2+bx+c,

where:

a=1, b=-6, and c=50

The zeroes are the x-intercepts, which are the values of x when y=0.

Substitute 0 for y.

0=x^2-6x+50

Quadratic Formula

x=(-b+-sqrt((b)^2-4ac))/(2a)

Plug in the known values.

x=(-(-6)+-sqrt((-6)^6-4*1*50))/(2*1)

Simplify.

x=(6+-sqrt(-164))/2

Prime factorize 164.

x=(6+-sqrt(2xx2xx41))/2

Simplify.

x=(6+-2sqrt(41)i)/2

Reduce.

x=(color(red)cancel(color(black)(6))^3+-color(red)cancel(color(black)(2))^1sqrt(41)i)/color(red)cancel(color(black)(2))^1

Simplify.

x=3+-sqrt(41)i

Values for x.

x=3+sqrt(41)i,3-sqrt(41)i