tính
a , 5/7 * 12/11 + 9/7 * 2/11 - 5/7 * 14/11
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a, \(\frac{7}{5}+\frac{9}{7}+\frac{6}{5}+\frac{11}{7}\)
C1: \(\frac{94}{35}+\frac{6}{5}+\frac{11}{7}=\frac{136}{35}+\frac{11}{7}=5\frac{16}{35}\)
C2: \(=\left(\frac{7}{5}+\frac{6}{5}\right)+\left(\frac{9}{7}+\frac{11}{7}\right)=\frac{13}{5}+\frac{20}{7}=5\frac{16}{35}\)
b,
C1 : \(\frac{8}{14}+\frac{2}{11}+\frac{12}{14}+\frac{31}{11}=\frac{4}{7}+\frac{2}{11}+\frac{6}{7}+\frac{31}{11}=\frac{58}{77}+\frac{6}{7}+\frac{31}{11}=\frac{124}{77}+\frac{31}{11}=4\frac{3}{7}\)
C2:
\(\frac{4}{7}+\frac{2}{11}+\frac{6}{7}+\frac{31}{11}=\left(\frac{4}{7}+\frac{6}{7}\right)+\left(\frac{2}{11}+\frac{31}{11}\right)=\frac{10}{7}+3=3\frac{10}{7}=4\frac{3}{7}\)
**** cko t nha , xin xin đó
\(a,-\dfrac{5}{9}+\dfrac{14}{9}=\dfrac{-5+14}{9}=\dfrac{9}{9}=1\\ b,\dfrac{2}{7}+\dfrac{8}{-3}\\ =\dfrac{2}{7}-\dfrac{8}{3}\\ =\dfrac{2.3-8.7}{21}\\ =\dfrac{6-56}{21}\\ =\dfrac{-50}{21}\\ c,\dfrac{9}{11}+\dfrac{5}{7}+\dfrac{20}{-11}+\dfrac{12}{25}+\dfrac{2}{7}\\ =\left(\dfrac{2}{7}+\dfrac{5}{7}\right)+\left(\dfrac{9}{11}-\dfrac{20}{11}\right)+\dfrac{12}{25}\\ =\dfrac{7}{7}-\dfrac{11}{11}+\dfrac{12}{25}\\ =1-1+\dfrac{12}{25}\\ =\dfrac{12}{25}\)
\(\frac{5}{7}.\frac{12}{11}+\frac{9}{7}.\frac{2}{11}-\frac{5}{7}.\frac{14}{11}\)
\(=\frac{1}{7}.\frac{1}{11}.\left(5.12+9.2-5.14\right)\)
\(=\frac{1}{77}.\left(60+18-70\right)\)
\(=\frac{1}{77}.8=\frac{8}{77}\)
a: \(=\dfrac{5}{7}\left(\dfrac{5}{11}+\dfrac{2}{11}-\dfrac{14}{11}\right)=\dfrac{5}{7}\cdot\dfrac{-7}{11}=-\dfrac{5}{11}\)
b: \(=\dfrac{12}{7}\left(19+\dfrac{5}{8}-15-\dfrac{1}{4}\right)=\dfrac{12}{7}\cdot\left(4+\dfrac{3}{8}\right)\)
\(=\dfrac{12}{7}\cdot\dfrac{35}{8}=\dfrac{3}{2}\cdot5=\dfrac{15}{2}\)
c: \(=\dfrac{2}{15}-\dfrac{2}{15}\cdot5+\dfrac{3}{15}=\dfrac{2}{15}\cdot\left(-4\right)+\dfrac{3}{15}=\dfrac{-8+3}{15}=\dfrac{-5}{15}=-\dfrac{1}{3}\)
d: \(=\dfrac{4}{9}\left(19+\dfrac{1}{3}-39-\dfrac{1}{3}\right)=\dfrac{4}{9}\cdot\left(-20\right)=-\dfrac{80}{9}\)
BÀI 1
a, \(5\times\frac{-7}{10}=\frac{-35}{10}=\frac{-7}{2}\)
b, \(\frac{4}{5}\times\frac{-7}{10}=\frac{-28}{50}=\frac{-14}{25}\)
c, \(\frac{4}{9}+\frac{4}{3}\times\frac{16}{4}=\frac{4}{9}+\frac{16}{3}=\frac{52}{9}\)
d, \(\frac{11}{22}-\frac{3}{9}\times\frac{14}{21}=\frac{11}{22}-\frac{2}{9}=\frac{55}{198}=\frac{5}{18}\)
BÀI 2
\(A=\frac{6}{13}\times\frac{5}{7}+\frac{6}{13}\times\frac{2}{7}+\frac{17}{13}\)
\(A=\frac{30}{91}+\frac{12}{91}+\frac{17}{13}\)
\(A=\frac{30}{91}+\frac{12}{91}+\frac{119}{91}\)
\(A=\frac{161}{91}=\frac{23}{13}\)
\(B=\frac{11}{15}\times\frac{4}{11}+\frac{11}{15}\times\frac{5}{11}+\frac{11}{15}\times\frac{2}{11}\)
\(B=\frac{4}{15}+\frac{1}{3}+\frac{2}{15}\)
\(B=\frac{11}{15}\)
\(C=\left(\frac{19}{64}-\frac{33}{22}+\frac{24}{51}\right)\times\left(\frac{1}{5}-\frac{1}{15}-\frac{2}{15}\right)\)
\(C=\frac{-797}{1088}\times0\)
\(C=0\)
\(D=\frac{8}{13}\times\frac{7}{12}+\frac{8}{13}\times\frac{5}{12}-\frac{1}{12}\)
\(D=\frac{14}{39}+\frac{10}{39}-\frac{1}{12}\)
\(D=\frac{83}{156}\)
bạn biết câu náy không (24 + 11) . {546 - [14 . (64 - 2^{3}3) : 2]} =
a) Dấu hiệu là điểm bài thi học kì của 100 học sinh lớp 7 của một trường Trung học Cơ Sở Hòa Bình. Số các dấu hiệu là 100
b) Bảng tần số
Giá trị (x) | 1 | 2 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | |
Tần số (n) | 2 | 1 | 2 | 4 | 6 | 8 | 9 | 10 | 13 | 11 | 8 | 8 | 4 | 6 | 3 | 2 | 3 | 1 | N=100 |
Nhận xét: Giá trị lớn nhất là 19, giá trị nhỏ nhất là 1; tần số lớn nhất là 13, tần số nhỏ nhất là 1.
Phương pháp giải:
Tính nhẩm rồi điền kết quả vào chỗ trống.
Lời giải chi tiết:
a)
7 + 5 = 12 5 + 7 = 12
4 + 9 = 13 9 + 4 = 13
8 + 7 = 15 7 + 8 = 15
2 + 9 = 11 9 + 2 = 11
b)
16 − 8 = 8 14 − 7 = 7
11 − 9 = 2 17 − 9 = 8
12 − 5 = 7 16 − 9 = 7
13 − 6 = 7 15 − 8 = 7
d=43/37d=43/37 × 23/15−43/3723/15−43/37 × 8/15+31/378/15+31/37
=43/37=43/37 x 23/15+43/3723/15+43/37 x (−8/15)+31/37(−8/15)+31/37
=43/37(23/15−8/15)+31/37=43/37(23/15−8/15)+31/37
=43/37.1+31/37=43/37.1+31/37
=2=2
E=−5/24E=−5/24 × 9/11−5/249/11−5/24 × 2/11+7/122/11+7/12
=−5/24(9/11+2/11)+7/12=−5/24(9/11+2/11)+7/12
=−5/24.1+7/12=−5/24.1+7/12
=3/8=3/8
a)3/7–−11/14−7/3×6/7a)3/7–−11/14−7/3×6/7
=3/7−−11/14−2=3/7−−11/14−2
=3/7+11/14−2=3/7+11/14−2
=−11/14=−11/14
b)6/5:3/2+−2/3×9/14b)6/5:3/2+−2/3×9/14
=4/5−3/7=4/5−3/7
=13/35
d=43/37d=43/37 × 23/15−43/3723/15−43/37 × 8/15+31/378/15+31/37
=43/37=43/37 x 23/15+43/3723/15+43/37 x (−8/15)+31/37(−8/15)+31/37
=43/37(23/15−8/15)+31/37=43/37(23/15−8/15)+31/37
=43/37.1+31/37=43/37.1+31/37
=2=2
E=−5/24E=−5/24 × 9/11−5/249/11−5/24 × 2/11+7/122/11+7/12
=−5/24(9/11+2/11)+7/12=−5/24(9/11+2/11)+7/12
=−5/24.1+7/12=−5/24.1+7/12
=3/8=3/8
a)3/7–−11/14−7/3×6/7a)3/7–−11/14−7/3×6/7
=3/7−−11/14−2=3/7−−11/14−2
=3/7+11/14−2=3/7+11/14−2
=−11/14=−11/14
b)6/5:3/2+−2/3×9/14b)6/5:3/2+−2/3×9/14
=4/5−3/7=4/5−3/7
=13/35
(5/7 + 9/7 - 5/7) = 9/7
12/11 + 2/11 - 14/11 =1
9/7 x 1 = 9/7