Expert: Abe Mantell - 7/2/2011

Question
"I am having difficulty with a few problems in my college algebra class. Thank you so much for your help.

1. (x-2)^2=20

What are the exact solutions? i got -4+squaroot of 80/2 and -4-squareroot of 8.944/2
x=

What are the approximate solutions? i got 2,6
x=

2. find the x-intercept and y-intercepts for f(x). f(x)=x^2-6x+1

x-intercepts are
y-intercept is

i got x-intercepts are (0,6)
I got y-intercept 0

3. Give exact and approximate solutions to three decimal places. x^2+18x+81=1

x=

I got x=-9,-9

4. solve by completing the square. x^2+13/2x=13
x=

I got x=squarroot of 377/16, -squarroot of 377/16"

Answer
Hello Colby,

Sorry for my delay, I was away for a few days and forgot to set "vacation" mode...

1. (x-2)^2=20 ==> x-2=(+ or -)sqrt(20) ==> x=2 (+ or -) sqrt(20)
.  which is about -2.4721 and 6.4721

2. f(x)=x^2-6x+1
.  y-intercept, let x=0...y=1 ==> (0,1)
.  x-intercept, let y=0 and solve for x. x^2-6x+1=0
.  Using the quadratic formula; x=3 (+ or -) sqrt(8) or about 5.82842 and 0.17157

3. x^2+18x+81=1 ==> x^2+18x+80=0 ==> (x+10)(x+8)=0 ==> x=-10, -8

4. -13/4+(1/4)*sqrt(377), -13/4-(1/4)*sqrt(377)

Abe