Which of the following is a factor of x^15 - 64

a) x^5 - 4
b) x^10 - 4x^5 + 16
c) x^10 - 4
d) x^15 + 8x + 16

A

Step-by-step explanation:

- 64 ← is a difference of cubes and factors in general as

a³ - b³ = (a - b)(a² + ab + b²)

Hence

- 64

= ()³ - 4³

= ( - 4)( + 4 + 16)

Thus A is a factor

x = ±sqrt(10)

step-by-step explanation:

5 - 2x² = -15

subtract 5 from each side

5-5 - 2x² = -15-5

-2x^2   = -20

divide by -2 on each side

-2x^2   /-2= -20/-2

x^2 =10

take the square root on each side

sqrt(x^2 )=±sqrt(10)

x = ±sqrt(10)

check:

5 - 2x² = -15

+sqrt(10)

5 - 2(sqrt(10))² = -15

5 -2(10) = -15

5 -20 = -15

-15 = -15

-sqrt(10)

5 - 2(-sqrt(10))² = -15

5 -2(10) = -15

5 -20 = -15

-15 = -15