Tính S= (2^4 + 1/4) (4^4 + 1/4).... (100^4+1/4) / (1^4+1/4) (3^4 +1/4) .... (99^4+1/4)
s=1*2*3*4+2*3*4*5+....+97*98*99*100.tính s ik
Tính nhanh :
a ) S = 2+4+6+8+.....+2018
b ) S= 10+102+103+...+10100
c) S=\(\frac{1}{5}+\frac{1}{5^2}+\frac{1}{5^3}+.....+\frac{1}{5^{100}}\)
d) S=\(\frac{1!}{3!}+\frac{2!}{4!}+\frac{3!}{5!}+....+\frac{2018!}{2020!}\)
biết rằng : n!=1×2×3×...×n
VD : 1! = 1
2! = 2.1
3!=1.2.3
4!=1.2.3.4
! : giai thừa
Tính nhanh :
a ) S = 2+4+6+8+.....+2018
b ) S= 10+102+103+...+10100
c) \(S=\frac{1}{5}+\frac{1}{5^2}+\frac{1}{5^3}+...+\frac{1}{5^{100}}\)
d) \(S=\frac{1!}{3!}+\frac{2!}{4!}+\frac{3!}{5!}+....+\frac{2018!}{2020!}\)
biết rằng : \(n!=1\times2\times3\times...\times n\)
VD : 1! = 1
2! = 2.1
3!=1.2.3
4!=1.2.3.4
! : giai thừa
cho S1=1+2
S2=3+4+5
S3=6+7+8+9
Tính S100
Tính nhanh 1*2*3+2*3*4+3*4*5+4*5*6+...+98*99*100
Tính nhanh, tính bằng cách hợp lí:
S=\(3+\frac{3}{1+2}+\frac{3}{1+2+3}+\frac{3}{1+2+3+4}+....+\frac{3}{1+2+3+...+100}\)
cmr P= 1/2^2 + 1/3^2 +1/4^4 + .... + 1/100^2
Tính \(A=1+4+4^2+...+4^{100}-\frac{4^{101}}{3}\)