Question

1.2+2.3+...+100.101

CÂU NÀY KHÓ QUÁ GIÚP

 

Answer 1

đặt biểu thức là A ta có:

A= 1.2+2.3+...+100.101

3A=1.2.3+2.3.3+...+100.101.3

3A=1.2.3+2.3.(4-1)+...+100.101.(102-99)

3A=1.2.3+2.3.4-1.2.3+...+100.101.102-99.100.101

3A=100.101.102

A=100.101.102/3

A=343400

duyệt nha

Answer 2

A= 1.2+2.3+....+100.101

3A=1.2.3+2.3.3+....+100.101.3

3A=1.2.(3-0)+2.3.(4-1)+.....+100.101.(102-99)

3A=1.2.3-0+2.3.4-1.2.3+..+100.101.102-99.100.101

3A=100.101.102

A=343400