Question

The expression (125 - x) = (5 - x) (x2 + ax + b). Find the value of a
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Answer 1

(125-x) = (5-x) (x^2+ax+b)

= 5x^2+5ax+5b-x^3-ax^2-bx

= -x^3-5ax^2+5ax+5b-b (125-x) = -x^3-5ax-bx+5b

= -x^3-5ax-bx+5b+x

= -x^2-5ax-bx+5b

= -x^2-5ax-bx+5b-125

5ax = -x^2-bx+5b-125

ax = -x^2-bx+5b-125/5

a = -x^2/x-bx+5b-25

= -x-bx+5b-25 --- 1

-×1 --- a = x+bx-5b+25

Finally, the value of a is x+bx-5b+25