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a)X x 62 + X x 38 = 4200 b) X x 186 - X x 86 = 3400
X x 62 + 38 =4200 X x 186 - 86 = 3400
X x 100 = 4200 X x 100 = 3400
X = 4200 : 100 X = 3400 : 100
X = 42 X = 34
c)X x 623 - X x 123 = 1000
X x 623 - 123 = 1000
X x 500 = 1000
X = 1000 : 500
X = 2
a, X x 186-Z x 86=3400
X x (186-86) =3400
X x 100=3400
X= 3400: 100
X= 34
b, X x 75+57 x X =32604
X x (75+57)=32604
X x 132=32604
X= 32604 : 132
X = 247
c, 216: X +34: X =10
(216+34) : X=10
250 : X =10
X= 250:10
X= 25
d, 2125:X -125 :X=100
(2125-125) :X= 100
2000: X=100
X= 2000:100
X= 20
a) \(x\times186-x\times86=3400\)
\(x\times\left(186-86\right)=3400\)
\(x\times100=3400\)
\(x=3400:100\)
\(x=34\)
b) \(x\times75+57\times x=32604\)
\(x\times\left(75+57\right)=32604\)
\(x\times132=32604\)
\(x=32604:132\)
\(x=247\)
c) 216 : x + 34 : x = 10
(216 + 34) : x = 10
250 : x = 10
x = 250 : 10
x = 25
d) 2125 : x - 125 : x = 100
(2125 - 125) : x = 100
2000 : x = 100
x = 2000 : 100
x = 20
\(7\times15=7\times5+7\times10\)
Không câu nào đúng
-----------------------
\(25\times16=25\times20-25\times4\)
Chọn A
1.
\(7\times15=7\times5+7\times3\)
Ở bài trên không có câu nào đúng.
2.
\(25\times16=25\times20-25\times4\)
Đáp án: \(A\)
a/ 34
b/ 247
c/ 25
d/ 20
T.I.C.K cho mình nha
Chúc bạn hok tốt
a: \(\dfrac{5}{3}\cdot\dfrac{7}{10}=\dfrac{5}{10}\cdot\dfrac{7}{3}=\dfrac{14}{3}>2\)
\(\dfrac{5}{7}:\dfrac{7}{10}=\dfrac{5}{7}\cdot\dfrac{10}{7}=\dfrac{50}{49}< 2\)
=>\(\dfrac{5}{3}\cdot\dfrac{7}{10}>\dfrac{5}{7}:\dfrac{7}{10}\)
b: \(\dfrac{4}{5}\cdot\dfrac{5}{6}=\dfrac{4}{6}=\dfrac{2}{3}\)
\(\dfrac{8}{9}:\dfrac{4}{3}=\dfrac{8}{9}\cdot\dfrac{3}{4}=\dfrac{8}{4}\cdot\dfrac{3}{9}=\dfrac{2}{3}\)
Do đó: \(\dfrac{4}{5}\cdot\dfrac{5}{6}=\dfrac{8}{9}:\dfrac{4}{3}\)
c: \(\dfrac{5}{11}\cdot\dfrac{33}{15}=\dfrac{5}{15}\cdot\dfrac{33}{11}=\dfrac{3}{3}=1\)
\(\dfrac{6}{17}\cdot\dfrac{34}{25}=\dfrac{34}{17}\cdot\dfrac{6}{25}=2\cdot\dfrac{6}{25}=\dfrac{12}{25}< 1\)
=>\(\dfrac{5}{11}\cdot\dfrac{33}{15}>\dfrac{6}{17}\cdot\dfrac{34}{25}\)
d: \(\dfrac{15}{19}\cdot\dfrac{38}{5}=\dfrac{15}{5}\cdot\dfrac{38}{19}=3\cdot2=6\)
\(\dfrac{15}{16}:\dfrac{3}{8}=\dfrac{15}{16}\cdot\dfrac{8}{3}=\dfrac{15}{3}\cdot\dfrac{8}{16}=\dfrac{5}{2}\)<6
=>\(\dfrac{15}{19}\cdot\dfrac{38}{5}>\dfrac{15}{16}:\dfrac{3}{8}\)
a) \(\frac{3}{16}+\frac{4}{15}+\frac{5}{16}+\frac{1}{15}\)
\(=\left(\frac{3}{16}+\frac{5}{16}\right)+\left(\frac{4}{15}+\frac{1}{15}\right)\)
\(=\frac{1}{2}+\frac{1}{3}\)
\(=\frac{5}{6}\)
b) \(\frac{6}{7}\times\frac{8}{15}\times\frac{7}{6}\times\frac{15}{16}\)
\(=\left(\frac{6}{7}\times\frac{7}{6}\right)\times\left(\frac{8}{15}\times\frac{15}{16}\right)\)
\(=1\times\frac{1}{2}=\frac{1}{2}\)
c) \(\frac{19}{20}\times\frac{13}{21}+\frac{9}{20}\times\frac{8}{21}\)
\(=\frac{19\times13}{20\times21}+\frac{9\times8}{20\times21}\)
\(=\frac{247}{420}+\frac{72}{420}\)
\(=\frac{319}{420}\)
a) 1400 : 20 - (17 + x) = 20
70 - (17 + x) = 20
17 + x = 70 - 20
17 + x = 50
x = 50 - 17
x = 33
b) 8 \(\times\) (x + 15) = 640
x + 15 = 640 : 8
x + 15 = 80
x = 80 - 15
x = 65
c) x \(\times\) 62 + x \(\times\) 38 = 4200
x \(\times\) (62 + 38) = 4200
x \(\times\) 100 = 4200
x = 4200 : 100
x = 42
d) x \(\times\) 186 - x \(\times\) 86 = 3400
x \(\times\) (186 - 86) = 3400
x \(\times\) 100 = 3400
x = 3400 : 100
x = 34