Question

1*2+2*3+3*4+4*5+.....+2015*2016

Answer 1

 toán lơp 6 nha mấy bạn giúp mình với

Answer 2

1.2+2.3+3.4+4.5+...+2015.2016

=>3(1.2+2.3+3.4+4.5+...+2015.2016)

=>1.2.3+2.3.3+3.4.3+4.5.3+...+2015.2016.3

=>1.2.(2+1)+2.3.(4-1)+3.4.(5-2)+...+2015.2016.(2017-2014)

=>1.2.2+1.2.1+2.3.4-2.3.1+3.4.5-3.4.2+...+2015.2016.2017-2015.2016.2014

=>2015.2016.2017

Answer 3

day dau phai toan lop 7?