A:About two degrees.
B:Come on, please.
C:It often snows.
若关于x的二元一次方程kx+3y=5有一组解是x=2y=1,则k的值是( )
先观察算式的特点再填空.
4+8+16=16×2﹣4=28
4+8+16+32=32×2﹣4=60
4+8+16+32+64=64×2﹣4=124
4+8+16+32+…+256=____
a+2a+4a+8a+16a+…+1024a=____