设方程x²+x-1=0的两个根是x1,x2,求4x1^5+10x2^3的值
问题描述:
设方程x²+x-1=0的两个根是x1,x2,求4x1^5+10x2^3的值
答
x1+x2=-1, x1x2=-14x1^5+10x2^3=4*(x1^2*x1^2*x1)+10*(x2^2*x2)=4*(1-x1)^2*x1+10*(1-x2)*x2=4(x1^2-2x1+1)*x1+10(x2+x2-1)=4(1-x1-2x1+1)*x1+10(2x2-1)=4(2-3x1)*x1+10(2x2-1)=4(2x1+3x1-3)+10(2x2-1)=20x1-12+20x2...