Question

18.(1)[x^4-33x^2-40x+244]/[x^2-8x+15]=5

Answer 1

(x^4-33x^2-40x+244)/(x^2-8x+15)=5

x^4-33x^2-40x+244=5x^2-40x+75

x^4-38x^2+169=0

Δ=(-38)^2-4•169=768

x^2=(38±√768)/2=19±8√3

x=√(19±8√3)

经检验,无增根,方程(x^4-33x^2-40x+244)/(x^2-8x+15)=5的根是√(19±8√3),即有x=√(19-8√3）==> (1);x=√（19+8√3）==> (1)