1) Tính nhanh
A = 1/99 - 1/99.98 - 1/98.97 - ............... - 1/3.2 - 1/2.1
2) Thực hiện phép tính :
( 3 - 1/4 + 2/3 ) - 5 +1/3 - 6/5 - ( 6 - 7/4 + 3/2 )
1. THỰC HIỆN PHÉP TÍNH :
a) -2/3+3/4--1/6+-2/5 ;
b) -2/3+-1/5+3/4-5/6- -7/10 ;
c)1/2- -2/5+1/3+5/7- -1/6+-4/35+1/41 ;
d) 1/100.99-1/99.98-1/98.97-...-1/3.2-1/2.1
tính nhanh tính hợp lý
a,1/3-3/4-(-3/5)+1/64-2/9-1/36+1/15
b,1/99-1/99.98-1/98.97-1/97.96...-1/3.2-1/2.1
1/99-1/99.98-1/98.97-.....-1/2.1
= 1/99-(1/99.98+1/98.97+......+1/2.1
=1/99-(1/99-1)
=1
TINH NHANH :
A= ( -1/2)-(-3/5)+(-1/9)+1/131-(-2/7)+4/35-7/18
B=1/99-1/99.98-1/98.97-...-1/4.3-1/3.2-1/2.1
a) 1/2 - (- 2/5) + 1/3 + 5/7 - (- 1/6) + (- 4/35) + 1/41
b) 1/ 100.99 - 1/ 99.98 - 1/ 98.97 - ..... - 1/ 3.2 - 1/ 2.1
b) \(\dfrac{1}{100.99}-\dfrac{1}{99.98}-\dfrac{1}{98.97}-...-\dfrac{1}{3.2}-\dfrac{1}{2.1}\)
\(=\dfrac{1}{100.99}-\left(\dfrac{1}{1.2}+\dfrac{1}{2.3}+...+\dfrac{1}{97.98}+\dfrac{1}{98.99}\right)\)
\(=\dfrac{1}{100.99}-\left(1-\dfrac{1}{2}+\dfrac{1}{2}-\dfrac{1}{3}+...+\dfrac{1}{97}-\dfrac{1}{98}+\dfrac{1}{98}-\dfrac{1}{99}\right)\)
\(=\dfrac{1}{100.99}-\left(1-\dfrac{1}{99}\right)\)
\(=\dfrac{1}{100.99}-\dfrac{98}{99}=-\dfrac{9799}{9900}\)
1/2+2/5+1/3+5/7+1/6+(-4/35)+1/41
đổi ra rồi nha bạn thế là tự biết làm được rồi
tính nhanh :
A = 1/3 - 3/4 -(-3/5) +1/72-2/9-1/36+1/15
B= 1/5 -3/7 +5/9 -2/11+7/13-9/16-7/13+2/11-5/9+3/7 -1/5
C= 1/100-1/100.99- 1/99.98-1/98.97......-1/3.2 - 1.2.1
Giúp mình với , mình cần gấp :
a) Tính nhanh :
A = 1/3 - 3/4 - ( - 3/5 ) + 1/72 -2/9 - 1/36 +1/15
b) Tính nhanh :
B = 1/5 - 3/7 + 5/9 - 2/11 + 7/13 - 2/11 - 5/9 + 3/7 - 1/5
c) Tính nhanh :
C = 1/100- 1/100.99 - 1/99.98 - 1/98.97 - ..............- 1/3.2 -1/2.1
c/
C = 1/100-1/100-1/99-1/99-1/98-1/98-1/97-..........-1/3-1/2-1/2-1/1
C = 1/100-1/100-1/1
C = 0-1/1
C = -1
Cần gấp mấy bn ơi:>>>
a,-2/3+3/4--1/6+-2/5
b,-2/3+-1/5=3/4-5/6- (-7/6)
c,1/2-(-2/5)+1/3+5/7-(-1/6)+(-4/35)+1/41
d,1/100.99-1/99.98-1/98.97-.....-1/3.2-1/2.1
Tính
a, (-2/3) + 3/4 -(-1/6)+(-2/5)
b, (-2/3) +(-1/5)+ 3/4 - 5/6- (-7/10)
c, 1/2 - (-2/5)+1/3+5/7-(01/6)+(-4/35) +1/41
d, (1/100.99) - (1/99.98)-(1/98.97)-...-(1,3.2)- (1/2.1)
1 thực hiện phép tính
a,\(\dfrac{-2}{3}+\dfrac{3}{4}-\dfrac{-1}{6}+\dfrac{-2}{6}-\dfrac{-2}{5}\)
b,\(\dfrac{-2}{3}+\dfrac{-1}{5}+\dfrac{3}{4}-\dfrac{5}{6}-\dfrac{-7}{10}\)
c,\(\dfrac{1}{2}-\dfrac{-2}{5}+\dfrac{1}{3}+\dfrac{5}{7}-\dfrac{-1}{6}+\dfrac{-4}{35}+\dfrac{1}{41}\)
d,\(\dfrac{1}{100.99}-\dfrac{1}{99.98}-\dfrac{1}{98.97}-...-\dfrac{1}{3.2}-\dfrac{1}{2.1}\)
Các câu dễ tự làm nha:
\(D=\dfrac{1}{100.99}-\dfrac{1}{99.98}-\dfrac{1}{98.97}-...-\dfrac{1}{3.2}-\dfrac{1}{2.1}\)
\(D=\dfrac{1}{99}-\dfrac{1}{100}-\dfrac{1}{99}+\dfrac{1}{98}-\dfrac{1}{98}+\dfrac{1}{97}-...-\dfrac{1}{2}+\dfrac{1}{3}-1+\dfrac{1}{2}\)\(D=-\dfrac{1}{100}-1\)