tính nhanh ( 11/4. -5/9 - 4/9 : 4/11). 8/33
tính nhanh
B=(11/4.-5/9-4/9:4/11).8/33
\(B=\left[\dfrac{11}{4}\cdot\left[-\dfrac{5}{9}-\dfrac{4}{9}\right]\right]\cdot\dfrac{8}{33}=\dfrac{11}{4}\cdot\dfrac{8}{33}\cdot\left(-1\right)=\dfrac{-2}{3}\)
Tính bằng cách hợp lý lớp 6
b) (11/4 . -5/9 - 4/9 . 11/4) . 8/33 Giúp mình với mình cảm ơn!!!
\(=\dfrac{11}{4}\cdot\left(-1\right)\cdot\dfrac{8}{33}=\dfrac{2}{3}\cdot\left(-1\right)=-\dfrac{2}{3}\)
b, (11/4 . -5/9-4/9 . 11/4).8/33
Tính nhanh : 1+2-3-4+5+6-7-8+9+10-11-12+13+...............+33
Giúp mình với nha các bạn !
1+2-3-4+5+6-7-8+9+................+33
=1+(2-3-4+5)+(6-7-8+9)+............+(30-31-32+33)
=1+0+0+..............+0
=1
1+2-3-3+5+6-7-8+9+10-11-12+13+...............+33
= 1 + ( 2-3-4+5)+(6-7-8+9)+......+(30-31-32+33)
=1
Dùng tính chất để tính
a) 17/5 . -31/125 . 1/2 . 10/17 . -1/23
b) (11/4 . -5/9 - 4/9 . 11/4) . 8/33
c) (17/28 + 18/29 - 19/30 - 20/31) . (-5/12 + 1/4 + 1/6)
d) -1/4 . 15^2/11 + 68/4 . -1/11
e) -9/25 . 53/3 - (-3/5)^2 .22/3
A=(11 phần 4 x -5 phần 9 -4 phần 9 chia 4 phần 11)x 8 phần 33
\(A=\left(\dfrac{11}{4}.\dfrac{-5}{9}-\dfrac{4}{9}:\dfrac{4}{11}\right).\dfrac{8}{33}\)
\(=\left(\dfrac{11}{4}.\dfrac{-5}{9}-\dfrac{4}{9}.\dfrac{11}{4}\right).\dfrac{8}{33}\)
\(=\left[\dfrac{11}{4}.\left(\dfrac{-5}{9}-\dfrac{4}{9}\right)\right].\dfrac{8}{33}\)
\(=\dfrac{11}{4}.\left(-1\right).\dfrac{8}{33}\)
\(=\dfrac{11.\left(-1\right).8}{4.33}=\dfrac{11.\left(-1\right).2.4}{4.3.11}=\dfrac{-2}{3}\)
Tính nhanh:
B=\(\left(\frac{11}{4}.\frac{-5}{9}-\frac{4}{9}:\frac{4}{11}\right).\frac{8}{33}\)
C=\(\frac{1}{10}+\frac{1}{15}+\frac{1}{21}+...+\frac{1}{120}\)
tính nhanh: (4/5-4/11+4/13)/(9/5-9/11+9/13)+(5/7+5/11-5/13)/(9/7+9/11-9/13)
ta có \(\frac{\frac{4}{5}-\frac{4}{11}+\frac{4}{13}}{\frac{9}{5}-\frac{9}{11}+\frac{9}{13}}+\frac{\frac{5}{7}+\frac{5}{11}-\frac{5}{13}}{\frac{9}{7}+\frac{9}{11}-\frac{9}{13}}\)
\(=\frac{4\left(\frac{1}{5}-\frac{1}{11}+\frac{1}{13}\right)}{9\left(\frac{1}{5}-\frac{1}{11}+\frac{1}{13}\right)}+\frac{5\left(\frac{1}{7}+\frac{1}{11}-\frac{1}{13}\right)}{9\left(\frac{1}{7}+\frac{1}{11}-\frac{1}{13}\right)}\)
\(=\frac{4}{9}+\frac{5}{9}=\frac{9}{9}=1\)
1/ Tính nhanh:
a. 5/7×5/11+5/11×2/9-5/7×17/11
b. 1×2+2×4+3×6+4×8+5×10/3×4+6×8+9×12+12×16+15×20
coi lại câu a
1.1+1.1+1.1+1.1+1.1/1.1+1.1+9.3+6.8+.2