Quadratic formula help, question difficulty?

Solution 1
x = [ - 8 ± √ (64) ] / 2
x = [ - 8 ± 8 ] / 2
x = 0 , x = - 8

Solution 2
( x ) ( x + 8 ) = 0
x = 0 , x = - 8

5^2-8x-12=9 set the equation equal to zero 5^2-8x-21=0 now plug in the numbers the discriminant first b^2-4ac 64+420 484 +/-22 rest of q.f. (-b+/-22)/2a (8+/-22)/10 30/10,-14/10 3,-7/5 need the factors? set x equal to the factor then solve for zero [no fractions] x=3 x-3=0 (x-3) x= -7/5 5x= -7 5x+7=0 (5x+7) (x-3)(5x+7)

x^2 +8x = 0.
quadratic equation form -> ax^2+bx+c=0
we have a= 1 , b =8 and c=0.
now use the formula
x= - b +- (sqroot b^2-4ac)/2a
so x= -8+(sqroot 64-0)/2*1 , = -8-(sqroot 64-0)/2*1
x= -8+8/2 , = -8-8/2
x=-0, = -8

In this case c=0.
Now just solve it using the formula.
Your ans will come 0 OR -8

You don't use the quadratic equation for this problem.

You can factor this:
x² + 8x = 0
x(x+8) = 0
x = 0, -8

Another method is completing the square by adding 16 to both sides.

x² + 8x = 0
x² + 8x +16 = 16
(x+4)² = √16

Take the square root of both sides
√(x+4)² = √16
x + 4 = ±4
x = ± 4 - 4
x = 4 - 4 or x = -4 -4
x = 0 or -8

You don't need the quadratic formula on this one.

x(x+8)=0

You are done. x=0 or -8

type a squre as ^2 the carat (^) signifies a power

x^2 + 8x +0 =0

by adding a zero, you do not change the equation, but you do add the "c" value necessary to complete the quadratic.

x^2 + 8x = 0
x(x + 8) = 0

x = 0

x + 8 = 0
x = -8

∴ x = 0 , -8

factor out x
and you get

x(x+8)

its way easier than quadratic formula

c=0

Look at it like this:

x²+8x+0=0