Question

3|4+3|28+3|70+3|130+3|208=找规律计算

Answer 1

=3/（1*4）+3/(4*7)+3/（7*10）+.3/(13*16)

=3(1/(1*4)+1/(4*7)+.1/(13*16))

=1-1/4+1/4-1/7+.+1/13-1/16

=1-1/16

=15/16