Question

5.
If the expression (125 – x^3) = (5 – x) (x² + ax + b),
then the value of 'a' is
(A) 4
(B) 2
(C) -7
(D) 5​

Answer 1

According to formula

${a}^{3} - {b}^{3} = (a - b) \: ( {a}^{2} + ab + {b}^{2} )$

here (a³)is 125 and b is (x³)

(125 - x³) = (5 - x ) ( {5}² + {5 }{x} + {x}²)

so value of a is 5 .

Note: cube of 5 is 125

so During expansion in had taken 125 as 5

Answer 2

see the attachment....