The factors of x8 - x7 - 30 are :(a) (x4 - 6) and (x4 - 5)(b) (x4 - 6)

1.	The factors of x8 - x7 - 30 are :(a) (x4 - 6) and (x4 - 5)(b) (x4 - 6) and (x4 + 5)(c) (x4 + 6) and (x4 - 5)(d) (x4 + 6) and (x4 + 5)
Answer» (b) (x⁴ + 5)(x⁴ - 6) x⁸ - x⁴ - 30 = x⁸ - 6x⁴ + 5x⁴ - 30 = x⁴(x⁴ - 6) + 5(x⁴ - 6) = (x⁴ + 5)(x⁴ - 6)

The factors of x8 - x7 - 30 are :(a) (x4 - 6) and (x4 - 5)(b) (x4 - 6) and (x4 + 5)(c) (x4 + 6) and (x4 - 5)(d) (x4 + 6) and (x4 + 5)

Answer»

(b) (x⁴ + 5)(x⁴ - 6)

x⁸ - x⁴ - 30

= x⁸ - 6x⁴ + 5x⁴ - 30

= x⁴(x⁴ - 6) + 5(x⁴ - 6)

= (x⁴ + 5)(x⁴ - 6)