3/10. (-5/9+ 3/5) -3/5)-3/10.(3/9+-2/5)
-2/5. (5/12-9/15)-2/5.(2/17+ -2/5
de bai: tinh nhanh
Tinh (2^3*5*7)*(5^2*7^3)/(2*5*7^2)^2
1)tinh va so sanh
a)A=(3+2)2 va B=23+52
b)C=(3+5)3 va D=33+53
2)thuc hien phep tinh:
22.5.[(52+23):11-2]-32.2
tINH 5 + 5^2 + 5^3+ 5^2006
biet n! =1*2**3*...*n . tinh 1*1!+2*2!+3*3!+4*4!+5*5!=?
tinh
2448:[119-(23-6)]
[130-3.(5.2^4-5^2.2)]:2^3
5^3.52+5^3.7^2-5^3
2^3.16-2^3.14+56
biiet n!=1*2*3*4........................n;
tinh 1*1!2*2!3*3!4*4!5*5!
tinh hop li:
a) 1+2+3...+20
b)1+3+5+...+21
c)2+5+8+...+2018 +2021
d)1*2+2*3+3*4+...+15*16
e)1*2*3+2*3*4+3*4*5+... +13*14*!5
tinh nhanh : 1/5-1/5^2+1/5^3+....+1/5^101