a^2-7a+1=0求代数式2a^2-13a+a^2+1分之7

a²-7a+1=0
所以a²=7a-1
a²+1=7a
所以原式=2(7a-1)-13a+7/7a
=a-2+1/a
=(a²-2a+1)/a
=(7a-2a)/a
=5a/a
=5

a²-7a+1=0
∴a²-7a=-1 a²+1=7a
∴2a^2-13a+a^2+1分之7
=2a²-14a+a+7/7a
=2(a²-7a)+(a²+1)/a
=-2+7
=5