Solve x2 + 8x + 15 = 0?

x2 + 8x = (-15) ==== x2 is the same as 2x so we switch the order.

2x + 8x = (-15) ==== Add 2x to 8x to get 10x

10x = (-15) ==== 10 goes into 15 exactly 1.5 times, to X= -1.5

Finnaly since a negative cannot be a variable, X = -1.5 is changed to X = 1.5.

I hope I helped and did not mess you up.

Here is a little info:

No fuss factoring: example

ax^2 +bx +c: –> 4x^2 + 11x + 6

(ax ) (ax ) –> (4x )(4x ) Multiply a and c: a*c,4*6=24

Find integers whose product is a*c, and whose sum equals b. Write these integers in the incomplete factors of step one.

24*1, 12*2, 6*4, 3*8, 1*24

Now b equals 11, which is 3+8 and 3*8=24 so the answer is :

(4x+8)(4x+3) Discard any common factors withing each parenthesis in the next step, the result is the end result:

(x+2)(4x+3)

If you memorize this method you should have an easier time.

X^ + 8x + 15 = 0

(X + 3 )(X + 5) = 0

X + 3 = 0

subtract 3 from each side

X + 5 = 0

subtract five from each side

x = -3, -5

(x+3)(x+5)=0

x=-3 or -5

B

x+5=0 , x+3=0

-5= -5, -3= -3

x= -5, x= -3

hope it helped

(x+5) (x+3) = 0

From this you can see that the answers are :

x = -5 and x = -3

the form of quadratic equation is ax2+bx+c=0

D=b2-4ac

x=(-b+^D)/2a and x=-b-^D/2a

SO:

D=64-60=4

x=(-8+^4)/2=3

and

x=(-8-^4)/2=-5

The correct answer is: A)3,-5