Question

Solve x2 − 8x − 20 = 0.

x = 4, x = −5
x = −4, x = 5
x = 2, x = −10
x = −2, x = 10

Answer 1

@mathmate @Teddyiswatshecallsme

Answer 2

you need to find 2 numbers whose product = -20 and whose sum = -8

Answer 3

these will be the values of a and b in the factors of the expression
(x + a)(x + b) = 0
you can then find the zeroes

Answer 4

try factoring -10 and see if you can make -8 from 2 of the factors

Answer 5

sorry thats -20 not -10

Answer 6

Ok I think I understand what you mean...... ok so -10 * 2 = -20....... and then I have to find a way to make -20 equal -8....?

Answer 7

you are on the right track
-10 and 2 is right
because -10 + 2 = -8

Answer 8

so that the factors are
(x - 10 )(x + 2)

Answer 9

Oh wow that was suprisingly simple.....

Answer 10

yea
when you expand the factors the -10*x and 2*x make -8x

Answer 11

Ah ok thanks man

Answer 12

yw
now to get the zeros you equate to 0
(x - 10)(x + 2) = 0

means that x-10 = 0 or x + 2 = 0

so the zeros are 10 and -2