1、π
2、2x-y+-2=0
1、sinx-cox=0
sinx=cosx
(1) tanx=1 x=π/4
(2) 2sinx+sinx/cosx-2cosx=2cosx+cosx/cosx-2cosx
=1
2、S3=a1+a2+a3
=a1+(a1+d)+(a1+2d)
=3a1+3d
3=3x(-3)+3d
d=4
an=a1+(n-1)d
=3+(n-1)x4
=4n-1
bn=4x2n
bn-1=4x2(n-1)
bn-bn-1=8
b1=8
Sn=n(b1+bn)/2
=n(8+8n)/2
=4n²+4n