已知n为自然数,且x的2n次方=3,求(-1/3x的3n次方)的4次方÷[4(x的3次方)的2n次方] 的值
问题描述:
已知n为自然数,且x的2n次方=3,求(-1/3x的3n次方)的4次方÷[4(x的3次方)的2n次方] 的值
答
1/12
(-1/3x的3n次方)的4次方÷[4(x的3次方)的2n次方]
=(-1/3)的4次方*(x的12n次方)/[4(x的6n次方)]
=(-1/3)的4次方*(x的6n次方)/4
=[(1/3)的4次方*(x的2n次方)的3次方]/4
=(x的2n次方)的3次方/(4*3的4次方)
=3^3/(4*3^4)
=1/(4*3)
=1/12
答
(-x/3)^12n+4x^6n=(-x)^12n/(3^12n)+4(x^6n)=3^6/3^(12n)+3^3=3^(-6)/3^n+27=729/3^n+27
答
(-1/3x^3n)^4/[4(x^3)^2n]=[1/81*x^(12n)]/[4x^(6n)]
=1/81*1/4*x^(6n)=1/81*1/4*[x^(2n)]^3
=1/81*1/4*(3^3)=1/12