Question

已知等差数列{an},+a+2+a+4=11,+a1+a2+a3+a6=多少？

已知等差数列，an, a 2+a 4=11 1+a 2+a 3+a 4.

Answer 1

等差数列a2+a4=a3-d+a3+d=2a3=11, 

a1+a2+a3+a6

=(a3-2d)+(a3-d)+a3+(a3+3d)

=4a3

=22

Answer 2

已知等差数列{an},a2+a4=11, a1+a2+a3+a6=多少？
a2+a4=11
a3=11/2=5.5
a1+2d=a3
a2+d=a3
a6=a3+3d
a1+a2+a3+a6=a3-2d+a3-d+a3+a3+3d
=4a3
=4*5.5=22