4/ 5 x 15/11 x 2/9
4/7 x 2/5 + 4/7 x 3/5
(5/7 + 7/8) x 2
2/14 + 3/7 - 3/14 x 2
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1/ Suy ra: -35 + 7x - 2x + 20 = 15
5x - 15 = 15
5x = 30
x = 6
2/ Suy ra: 4x - 20 - 3x - 21 = -19
x - 41 = -19
x = 22
3/ Suy ra: 8 - 4x + 3x - 15 = 14
-7 -x = 14
x = -7 -14
x = -21
4/ Suy ra: 7x - 63 - 30 + 5x = -6 + 11x
7x + 5x - 11x = -6 +63 + 30
x = 87
5/ Suy ra: -21x +35 + 14x - 28 = 28
-21x + 14x = 28 +28 - 35
-7x = 21
x= -3
6/ Suy ra: 20 - 5x + 7x - 14 = -2
2x = -8
x = -4
7/ Suy ra: 4x +15 -5x = 7
-x = -8
x = 8
8/ Suy ra: 5x - 35 +30 -10x = 20
-5x - 5 = 20
-5x = 25
x = -5
9/ Suy ra: 35 - 7x + 5x - 10 = 15
-7x + 5x = 15 +10 - 35
-2x = -10
x = 5
a: \(A=\dfrac{-7}{28}\cdot\dfrac{15}{25}=\dfrac{-1}{4}\cdot\dfrac{3}{5}=\dfrac{-3}{20}\)
b: \(B=\dfrac{-5\cdot7}{14\cdot\left(-3\right)}=\dfrac{35}{42}=\dfrac{5}{6}\)
c: \(C=\dfrac{-1}{5}-\dfrac{1}{5}\cdot\dfrac{3}{5}=\dfrac{-1}{5}-\dfrac{3}{25}=\dfrac{-8}{25}\)
d: \(D=\dfrac{-3}{4}-\dfrac{1}{4}=-1\)
e: \(E=\dfrac{-4}{5}\left(1-\dfrac{15}{16}\right)=\dfrac{-4}{5}\cdot\dfrac{1}{16}=\dfrac{-1}{20}\)
f: \(F=\dfrac{6-7}{4}\cdot\dfrac{4+12}{22}=\dfrac{-1}{4}\cdot\dfrac{8}{11}=\dfrac{-2}{11}\)
\(\dfrac{7}{2}+\dfrac{2}{25}=\dfrac{7\times25}{2\times25}+\dfrac{2\times2}{25\times2}=\dfrac{175}{50}+\dfrac{4}{50}=\dfrac{179}{50}\)
\(\dfrac{23}{5}-\dfrac{11}{3}=\dfrac{23\times3}{5\times3}-\dfrac{11\times5}{3\times5}=\dfrac{69}{15}-\dfrac{55}{15}=\dfrac{14}{15}\)
\(\dfrac{3}{7}-\dfrac{1}{14}=\dfrac{3\times2}{7\times2}-\dfrac{1}{14}=\dfrac{6}{14}-\dfrac{1}{14}=\dfrac{5}{14}\)
\(\dfrac{8}{5}:\dfrac{1}{3}=\dfrac{8}{5}\times3=\dfrac{8\times3}{5}=\dfrac{24}{5}\)
\(2:\dfrac{5}{3}=2\times\dfrac{3}{5}=\dfrac{2\times3}{5}=\dfrac{6}{5}\)
\(\dfrac{4}{5}\times\dfrac{7}{15}=\dfrac{4\times7}{5\times15}=\dfrac{28}{75}\)
Lời giải:
\(\frac{7}{2}+\frac{2}{25}=\frac{7\times 25+2\times 2}{2\times 25}=\frac{179}{50}\)
\(\frac{23}{5}-\frac{11}{3}=\frac{23\times 3-5\times 11}{5\times 3}=\frac{14}{15}\)
\(\frac{3}{7}-\frac{1}{14}=\frac{6}{14}-\frac{1}{14}=\frac{6-1}{14}=\frac{5}{14}\)
\(\frac{8}{5}: \frac{1}{3}=\frac{8}{5}\times 3=\frac{24}{5}\)
$2: \frac{5}{3}=\frac{2\times 3}{5}=\frac{6}{5}$
$\frac{4}{5}\times \frac{7}{15}=\frac{28}{75}$
nhiều quá :((
\(a,2\left(x-5\right)-3\left(x+7\right)=14\)
\(2x-10-3x-21=14\)
\(-x-31=14\)
\(-x=45\)
\(x=45\)
\(b,5\left(x-6\right)-2\left(x+3\right)=12\)
\(5x-30-2x-6=12\)
\(3x-36==12\)
\(3x=48\)
\(x=16\)
\(c,3\left(x-4\right)-\left(8-x\right)=12\)
\(3x-12-8+x=0\)
\(4x-20=0\)
\(4x=20\)
\(x=5\)
Cố nốt nha bn !
cảm ơn, bn nha:)))
mà hình như bạn TOP 3 trả lời câu hỏi pải ko nhỉ???
A) 7/38 x 9/11 +7/38 x 4/11 -7/38 x 2/11
=7/38.(9/11+4/11-2/11)
=7/38
B) 5/31 x 21/25 + 5/31 x -7/10 - 5/31 x 9/20
=5/31.(21/25-7/10-9/20)
=5/31.(-31/100)
=-1/20
4/5 x 15/11 x 2/9 = 8/33
4/7 x 2/5 + 4/7 x 3/5 = 4/7
( 5/7 + 7/8 ) x 2 = 89/28
2/14 + 3/7 - 3/14 x 2 = 1/7
tk mình nhé, mk nhanh nhất
4/5 x 15/11 x2/9
= 4x15x2/5x11x9
= 4x5x3x2/5x11x3x3
= 8/33