Question

factorise
$x3 + x2 - 17x + 15$
​

Answer 1

Answer:

x 3 +x 2

−17x+15

x=−5

⇒(−5)

3 +(−5) 2

−17(−5)+15=0

∴(x+5) is a factor

∴(x 2 −4x+3)(x+5)

=(x 2 −3x−x+3)(x+5)

=(x(x−3)+1(x−3))(x+5)

=(x+5)(x+1)(x−3)