f.4 maths

x+2 is the factor of 2x^4 + 11x^3 -5x^2 -98x -120
=> f(x) = (x+2)g(x) => g(x) = (2x^3 + 7x^2 - 19x -60)

g(3) = 0 => g(x) = h(x) (x-3) => h(x) = (2x^2 + 13x +20) = (x+4)(2x+5)

=> f(x) = (x+2) (x-3) (x+4) (2x+5)

if x-1 is a cmmon factor of f(x)=2x^3 -x^2 -ax +b and g(x)= bx^3 -3x^2 -x +a

f(1) = 0 and g(1) = 0 => 2-1-a +b =0 and b -3 -1 +a = 0

=> 1 -a +b = 0 and b - 4 +a = 0
=> 1+b + b -4 = 0 => 2b - 3 = 0 +> b = 3/2

=> a = 4-b = 4 - 3/2 = 5/2

這裏可以幫到你
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