factorise using factor theorem x cube+7x square+7x-15
Answers
Answer:
Step-by-step explanation:
x³ + 7x² + 7x - 15
x = 1
= 1³ + 7(1)² + 7(1) - 15
= 1 + 7 + 7 - 15
= 15 - 15
= 0
Hence x - 1 is one of the factor
x² + 8x + 15
_______________
x - 1 _| x³ + 7x² + 7x - 15 |_
x³ - x²
_____________
8x² + 7x - 15
8x² - 8x
______________
15x - 15
15x - 15
____________
0
_______
x³ + 7x² + 7x - 15 = (x - 1)(x² + 8x + 15)
x² + 8x + 15
= x² + 5x + 3x + 15
= x(x + 5) + 3(x + 5)
= (x + 5)(x + 3)
x³ + 7x² + 7x - 15 = (x-1)(x + 5)(x + 3)
Answer:
I hope it's help you in study dear thanks
