Question

x cube minus 3 x square - 9 x - 5 factorise this

Answer 1

p(x) = x3 - 3x2 - 9x - 5

Factors of 5 = 1,5,-1,-5

p(1) = 13 - 3 x (1)2 - 9 x (1) - 5

= 1 -3 - 9 - 5

= 1 - 17 = - 16 ≠ 0

p(-1) = (-1)3 x 3 x (-1)2 - 9 x (-1) -5

= -1 - 3 + 9 - 5 = -9 + 9 = 0

p(-1) =0

∴ (x+1) is a factor of p(x)

p(x) ÷ (x+1)

x3 - 3x2 - 9x - 5 ÷ x + 1

= x2 - 4x - 5

x2 - 4x - 5

x2 - 5x + 1x - 5

= x ( x - 5) + 1 ( x - 5)

= ( x - 5) ( x + 1)

Please rate my answer. If it helps you.

Answer 2

Answer below!!




IF THE PICTURE IS NOT CLEAR.. I COULD PROVIDE U WITH AN ANOTHER PICTURE!!

HOPE THE ANSWER IS HELPFUL TO U!! :)