Question

(X-1) (x-2) are the factors of x^3-ax^2+bx-8 find a and b

Answer 1

Answer:

Let  f(x)=x3−ax2+bx−8 .

So ,  f(1)=f(2)=0.  

f(1)=1−a+b−8=0⟹b=a+7  

f(2)=8−4a+2b−8=0⟹b=2a  

⟹a=7,b=14 .

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