Tính nhanh A = ( 11/4 x -5/9 - 4/9 : 4/11)
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 \(\frac{\frac{4}{5}-\frac{4}{11}+\frac{4}{13}}{\frac{9}{5}-\frac{9}{11}+\frac{9}{13}}+\frac{\frac{5}{7}+\frac{5}{11}-\frac{5}{13}}{\frac{9}{7}+\frac{9}{11}-\frac{9}{13}}\)
\(=\frac{4\left(\frac{1}{5}-\frac{1}{11}+\frac{1}{13}\right)}{9\left(\frac{1}{5}-\frac{1}{11}+\frac{1}{13}\right)}+\frac{5\left(\frac{1}{7}+\frac{1}{11}-\frac{1}{13}\right)}{9\left(\frac{1}{7}+\frac{1}{11}-\frac{1}{13}\right)}\)
\(=\frac{4}{9}+\frac{5}{9}=\frac{9}{9}=1\)
tính nhanh các hỗn số , phân số .... sau:
A = 11 3/13 -(2 và 4/7 +5 3/13)
B = 6 4/9 + 3 7/11)-4 4/9
C = -5/7 x 2/11 + -5/7 x 9/11 +1 5/7
D = 0,7 x 2 2/3 .20 x0,375 x5/28
A= \(11\frac{3}{13}-\left(2\frac{4}{7}+5\frac{3}{13}\right)\)
= \(11\frac{3}{13}-2\frac{4}{7}-5\frac{3}{13}\)
= \(\left(11\frac{3}{13}-5\frac{3}{13}\right)-2\frac{4}{7}\)
= \(6-2\frac{4}{7}\)
= \(3\frac{3}{7}\)
B= \(\left(96\frac{4}{9}+3\frac{7}{11}\right)-4\frac{4}{9}\)
= \(96\frac{4}{9}+3\frac{7}{11}-4\frac{4}{9}\)
= \(\left(96\frac{4}{9}-4\frac{4}{9}\right)+3\frac{7}{11}\)
= \(92+3\frac{7}{11}\)
= \(95\frac{7}{11}\)
C= \(\frac{-5}{7}.\frac{2}{11}+\frac{-5}{7}.\frac{9}{11}+1\frac{5}{7}\)
= \(\frac{-5}{7}.\left(\frac{2}{11}+\frac{9}{11}\right)+1\frac{5}{7}\)
= \(\frac{-5}{7}.1+1\frac{5}{7}\)
= \(\frac{-5}{7}+1\frac{5}{7}\)
= 1
(ý D bn tự làm ha)
mình vieetts ra thì dài lám
nếu bạn đã chác chăn về kiến thức thì hãy phân tích rồi tìm cách lam
còn ngược lại ban hãy tính máy tính rồi đoán cách làm cũng được
Tính nhanh
11/9 x 15/4 - 11/4 x 7/9 - 11/9 x 5/4
Tính nhanh :
3/4 x 4/9 x 9/11 x 22/25 x 5/7 : 10/7
\(=\dfrac{3}{9}\cdot\dfrac{9}{11}\cdot\dfrac{22}{25}\cdot\dfrac{5}{7}\cdot\dfrac{7}{10}=\dfrac{3}{11}\cdot\dfrac{22}{25}\cdot\dfrac{5}{10}=3\cdot2\cdot\dfrac{1}{2}\cdot\dfrac{1}{5}=\dfrac{3}{5}\)
\(=\dfrac{3x4x9x11x2x5x7}{4x9x11x5x5x10}=\dfrac{3x2x7}{10}=\dfrac{42}{10}=\dfrac{21}{5}\)
=3/9⋅9/11⋅22/25⋅5/7⋅7/10=3/11⋅22/25⋅5/10=3⋅2⋅1/2⋅1/5=3/5
tính nhanh ( 11/4. -5/9 - 4/9 : 4/11). 8/33
bài 1: tính nhanh:
A = 4/1*3*5+4/3*5*7+4/5*7*9+4/7*9*11+4/9*11*13
giúp mik nha !! Mik cảm ơn nhiều
\(A=\frac{1}{1.3}-\frac{1}{3.5}+\frac{1}{3.5}-\frac{1}{5.7}+...+\frac{1}{9.11}-\frac{1}{11.13}\)
\(\Leftrightarrow A=\frac{1}{1.3}-\frac{1}{11.13}=\frac{1}{3}-\frac{1}{143}=\frac{140}{429}\)
\(A=\frac{4}{1.3.5}+\frac{4}{3.5.7}+\frac{4}{5.7.9}+\frac{4}{7.9.11}+\frac{4}{9.11.13}\)
\(\Rightarrow A=\frac{1}{1.3}-\frac{1}{3.5}+\frac{1}{3.5}-\frac{1}{5.7}+...+\frac{1}{9.11}-\frac{1}{11.13}\)
\(\Rightarrow A=\frac{1}{1.3}-\frac{1}{11.13}=\frac{1}{3}-\frac{1}{143}=\frac{140}{429}\)
A =\(\frac{4}{1.3.5}+\frac{4}{3.5.7}+\frac{4}{5.7.9}+\frac{4}{7.9.11}+\frac{4}{9.11.13}\)
= \(\frac{1}{1.3}-\frac{1}{3.5}+\frac{1}{3.5}-\frac{1}{5.7}+\frac{1}{5.7}-\frac{1}{7.9}+\frac{1}{7.9}-\frac{1}{9.11}+\frac{1}{9.11}-\frac{1}{11.13}\)
= \(\frac{1}{1.3}-\frac{1}{11.13}\)
= \(\frac{1}{3}-\frac{1}{143}\)
= \(\frac{140}{429}\)
Dấu "." là dấu nhân
Tính nhanh
A=4/3*5+4/5*7+4/7*9+4/9*11
= 5/7.(5/11-2/11-14/4)
=5/7.(-71/22)= -355/154
A=\(\frac{5}{7}\)x\(\frac{5}{11}\)-\(\frac{5}{7}\)x\(\frac{2}{11}\)-\(\frac{5}{7}\)x\(\frac{14}{4}\)
A= \(\frac{5}{7}\)x(\(\frac{5}{11}\)-\(\frac{2}{11}\)-\(\frac{14}{4}\))
A=\(\frac{5}{7}\)x(\(\frac{3}{11}\)-\(\frac{14}{4}\))
A=\(\frac{5}{7}\)x\(\frac{-71}{22}\)
A=\(\frac{-355}{154}\)
Thực hiện phép tính ( tính nhanh nếu có thể )
a, -5/21 + -2/21 + 8/24
b, 4/11 . -2/7 + 4/11 . -4/7 + 4/11 . -1/7
c, \(10\dfrac{5}{9}\) - ( \(3\dfrac{5}{7}\) + \(4\dfrac{5}{9}\) )
d, 1/3 + \(1\dfrac{3}{4}\) - ( \(1\dfrac{3}{4}\) - 80% )
e, \(5\dfrac{3}{5}\) + \(7\dfrac{21}{48}\) : 10/7 - \(5\dfrac{21}{48}\) : 10/7
f, -5/7 . 2/11 - 5/11 . 9/7 + \(2\dfrac{5}{7}\)
g, -3/13 . 6/8 + 7/13 . -3/8 + \(1\dfrac{3}{8}\)
a: =-1/3+1/3=0
b: \(=\dfrac{4}{11}\left(-\dfrac{2}{7}-\dfrac{4}{7}-\dfrac{1}{7}\right)=\dfrac{4}{11}\cdot\left(-1\right)=-\dfrac{4}{11}\)
c: \(=10+\dfrac{5}{9}-3-\dfrac{5}{7}-4-\dfrac{5}{9}=3-\dfrac{5}{7}=\dfrac{16}{7}\)
d: \(=\dfrac{1}{3}+\dfrac{7}{4}-\dfrac{7}{4}+\dfrac{4}{5}=\dfrac{1}{3}+\dfrac{4}{5}=\dfrac{5+12}{15}=\dfrac{17}{15}\)
a: =-1/3+1/3=0
b: =10+59−3−57−4−59=3−57=167=10+59−3−57−4−59=3−57=167
d:
12+3/7-11+3/7 tính bằng cách thuận tiện nhé
tính nhanh
2/5+2/7-2/9-2/11
----------------------
4/5+4/7-4/9-4/11
\(\frac{\frac{2}{5}+\frac{2}{7}-\frac{2}{9}-\frac{2}{11}}{\frac{4}{5}+\frac{4}{7}-\frac{4}{9}-\frac{4}{11}}\)
\(=\frac{2\cdot\left(\frac{1}{5}+\frac{1}{7}-\frac{1}{9}-\frac{1}{11}\right)}{4\cdot\left(\frac{1}{5}+\frac{1}{7}-\frac{1}{9}-\frac{1}{11}\right)}\)
\(=\frac{2}{4}=\frac{1}{2}\)