Factor −20x² + x + 12.

1 answer:

4 0

The answer is -(5x-4)(4x+3)

Factor out a negative from the entire expression

−20x² + x + 12
= −(20x² - x - 12)

Find two numbers so that they

⇒ Multiply to get 20 * -12 = -240
⇒ and add to get -1 (coefficient on x term)

These two numbers are -16 and 15 (not very obvious; might have to crunch some numbers)

We can break down the x term using -16 and 15 as coefficients on x

−(20x² - x - 12)
= −(20x² - 16x + 15x - 12)

We factor by grouping. Factor 4x out of 20x² - 16x and 3 out of 15x - 12 to get

= −[ 4x(5x - 4) + 3(5x - 4) ]

Factor out (5x-4) to get

= -(5x-4)[4x + 3]
= -(5x-4)(4x+3)

You might be interested in

In a two-digit number, the tens digit is 5 less than the units digit. The number itself is five more than three times the sum of

Luden [163]

Given:

In a two-digit number, the tens digit is 5 less than the units digit.

The number itself is five more than three times the sum of its digits.

To find:

The number.

Solution:

Let the two digit number is ab. So,

$ab=10a+b$