Question

s=1.3+2.4+3.5+...+99.101

Answer 1

1.3+2.4+3.5+........+99.101
=3+8+15+.....+9999
+>số số hạng của phép tính là (9999-3):5+1=2000,2
=(9999+3).2000,2:2=10003000,2

Answer 2

mik trả lời lại nhá

A=1.3+2.4+3.5+...+99.101A=1.3+2.4+3.5+...+99.101

A=1.(2+1)+2.(3+1)+3.(4+1)+...+99.(100+1)A=1.(2+1)+2.(3+1)+3.(4+1)+...+99.(100+1)

A=1.2+1+2.3+2+3.4+3+...+99.100+99A=1.2+1+2.3+2+3.4+3+...+99.100+99

A=(1.2+2.3+3.4+...+99.100)+(1+2+3+...+99)A=(1.2+2.3+3.4+...+99.100)+(1+2+3+...+99)

Đặt B=1.2+2.3+3.4+...+99.100B=1.2+2.3+3.4+...+99.100

3B=1.2.3+2.3.3+3.4.3+...+99.100.33B=1.2.3+2.3.3+3.4.3+...+99.100.3

3B=1.2.3+2.3.(4−1)+3.4.(5−2)+...+99.100.(101−98)3B=1.2.3+2.3.(4−1)+3.4.(5−2)+...+99.100.(101−98)

3B=1.2.3+2.3.4−1.2.3+3.4.5−2.3.4+...+99.100.101−98.99.1003B=1.2.3+2.3.4−1.2.3+3.4.5−2.3.4+...+99.100.101−98.99.100

3B=99.100.1013B=99.100.101

B=99.100.101:3B=99.100.101:3

B=333300B=333300

Đặt C=1+2+3+...+99C=1+2+3+...+99

C=(99+1).99:2=4950C=(99+1).99:2=4950

Vậy A = 333 300 + 4 950 =338 250

Answer 3

ây dô moa đờ phắc cơ