Tính nhanh nếu có thể
( 6 : 3/5 - 7/6 x 6/7 ) : ( 21/5 x 10/11 + 57/11 )
a) -5/11 + ( -6/11 + 1 )
b) -13/17 + ( 13/-21 + -4/17 )
c) -5/12 . 7/-17 . 9/-20
d) 13/17 . 4/-5 + 13/17 . -3/4
e) -5/7 . 2/11 + -5/7 . 9/11 + 5/7
f) -2/5 . (-6) + 3/4 . 4/-10
B1.Tìm A/B biết:
A=4/(7*31)+6/(7*41)+9/(10*41)+7/(10*57)
B=7/(19*31)+5/(19*43)+3/(23*43)+11/(23*57)
B2:CMR:
A=1/52+2/53+3/54+...+11/512 <1/16
Rút gọn biêu thức
A=3^2.45^4-15^3.9^3/3^3.45^4-5^4.3^10
B=6^30.3^11.7-2^31.5.3^40/2^28.17.3^38-6^27.3^11
C=35.27^8+70.9^11/15.81^6-60.3^20
D=4^6.6^7-9^3.8^6/12^5.2^8+18^3.32^3
cho A = 4/(7*31)+6/(7*41)+9/(10*41)+11/(10*57)
B = 7/(19*31)+5/(19*43)+3(23*43)+11/(23*57)
tính tỉ A/B
A, 7 x - x = 5^21 : 5^19 + 3 . 2^2 - 7^0
B, 6 x + x = 5^11 : 5^19 + 3^1
C, 7 x - 2x = 6^17 : 6^15 + 44:11
cho A= 4/31*7 + 6 / 7*41 + 9/10 * 41 + 7/ 10 * 57
B= 7/19*31 + 5/19*43 + 3/23*43 + 11/23*57
tính phân số A/B
H=1/2+1/2^2+1/2^3+...+1/2^2004
I=4/31*7+6/7*41+9/10*41+7/10*57
K=7/19*31+5/19*43+11/23*57
M=4/5*8+4/8*11+3/11*14+...+305*308
Giúp mình nhé!!!