# ALGEBRA 1

posted by
**DANIELLE** on
.

Solve by whatever Method

1. X^2 +8X = -16

X^2 +8X +16 = -16 +16

(X +4)^2 =0

X+4 =+/- SQRT 0

X=-4+/- 0

X=-4, X=4

2. 3x^2-2x-5=0

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

2a a=3 ,b=-4,c=-5

X=-(-2)+/- Sqrt (-2)^2-4(3)(-5)

2(3)

X=2+/sqrt64 = 2+/-8

6

X= 2+8=10/6=1 2/3, x=2-8=-6/6=-1

Solution set is 1 2/3, -1

Solve by completing the square

3. X^2-x-1=0

X^2-x=1

X^2-1/2x=1/2

X^2-1/2x+ (1/2)^2=1/2 +(1/2)^2

X^2x+1/4=1/2+1/4

(X-1/4)^2=1/2

X-1/4=+/1/2

x=1/2+/-1/2

x=1, x=0

Just want to see if I am on the right path. Thanks Much!!!

#1, OL

#3, look at lines 5 and 6

1/2 + 1/4 = 3/4 not 1/2, take it from there

in #2 you are guilty of "bad form"

you have X= 2+8=10/6=1 2/3, x=2-8=-6/6=-1

using the = sign means that whatever you just wrote is equal to the next part.

I see x = 2+8 = 10/6..

2+8 is not equal to 10/6, you can't just drop numbers and then bring them back

that line should have read:

x=(2+8)/6 or x =(2-8)/6

x=10/6 or x=-6/1

x=5/3 or x = -1