已知x=4-根号3,求(x的四次方-6x的三次方-2x² 18x 23...
已知x=4-根号3,求(x的四次方-6x的三次方-2x² 18x 23)/(x²-8x 15)的值
x=4-√3
x-4=-√3(平方)
x²-8x 16=3
x²-8x 13=0
(x^4-6x^3-2x^2 18x 23)/(x^2-8x 15)
=[x^2(x^2-8x 13) 2x^3-15x^2 18x 23]/(x^2-8x 15)
=[2x(x^2-8x 13) x^2-8x 23]/(x^2-8x 15)
=[x^2-8x 23]/(x^2-8x 13 2)
=(x^2-8x 13 10)/(0 2)
=(0 10)/2
=5
问:选择题已知loga(根号3-根号2)=-1,则a等于( ) 1、根号3-根号2 2、根号2+根号3 3、根号2-根号3 4、-根号2-根号3
答:2、根号2+根号3 loga(√3-√2)=-1,则√3-√2=1/a,所以a=√3+√2详情>>
答:详情>>