Question

Factor completely: 10x2 + 2x − 8

Answer 1

The answer is 2(5x - 4)(x + 1)

10x² + 2x - 8 = 2*5x² + 2*x  - 2*4 =
                     = 2(5x² + x - 4) =
                     = 2(5x² + 5x - 4x - 4) =
                     = 2(5x *x + 5x*1) - (4*x + 4*1) =
                     = 2(5x(x + 1) - 4(x + 1)) =
                     = 2(5x - 4)(x + 1) 

Answer 2

Answer:

The answer is 2(5x - 4)(x + 1)

Step-by-step explanation:

In this case, use the shortcut, since (a - b + c) = 0. One factor is (x + 1) and the other is (x + c/a = - 8/10).

y = (x + 1)(10x - 8) = 2(x + 1)(5x - 4)

You may also use the new AC Method.

Converted

y

'

=

x

2

+

2

x

−

80

=

(

x

−

p

'

)

(

x

−

q

'

)

.

Factor pairs of (-80) -> ...(-4, 20)(-8, 10). This sum is 2 = b. Then p' = -8 and q' = 10.

Then,

p

=

p

'

a

=

−

−

8

10

and

q

=

q

'

a

=

10

10

=

1

.

y = 10(x - 8/10)(x + 1) = (10x - 8)(x + 1)= 2(5x - 4)(x + 1)