Question

Write the polynomial x^2-2x-15 in factored form

Answer 1

(x - 5)(x + 3)

Explanation:

x^2 - 2x - 15

(x - 5)(x + 3)

Answer 2

( x + 3 ) ( x - 5 )

Explanation:

When factorising quadratic equations you have to remember 3 things. Factors , sum and product. The standard way quadratic equation are formed is ax² + bx + c

→ The sum is the 'b' value, two number which add to this

The product is the 'c' value, two number which multiply to this

x² - 2x - 15

We need to two numbers which add to -2 and multiply to -15. Those two numbers are -5 and 3 so

x² - 5x + 3x - 15

→ Take out the factors separately

x ( x - 5 ) + 3 ( x - 5 )

( x + 3 ) ( x - 5 )