Question

\(\frac{1}{2}+\frac{5}{6}-\frac{3}{8}\)

\(\frac{10}{15}.\frac{7}{4}+\frac{7}{4}.\frac{9}{15}-\frac{4}{15}.\frac{7}{4}\)

\(\left(\frac{4}{5}+\frac{1}{2}\right).\left(\frac{3}{13}-\frac{8}{13}\right)\)

Tìm số nguyên x, bt:

a/ 3x-12=30                       b/

\(\frac{2}{3}x+\frac{1}{4}=\frac{7}{12}\)

c/ 2x² =32

giúp em nhé mai em thi!

Answer 1

\(\frac{1}{2}+\frac{5}{6}-\frac{3}{8}\)

\(=\frac{12}{24}+\frac{20}{24}-\frac{9}{24}\)

\(=\frac{23}{24}\)

\(\frac{10}{15}\cdot\frac{7}{4}+\frac{7}{4}\cdot\frac{9}{15}-\frac{4}{15}\cdot\frac{7}{4}\)

\(=\frac{7}{4}\cdot\left(\frac{10}{15}+\frac{9}{15}-\frac{4}{15}\right)\)

\(=\frac{7}{4}\cdot1=\frac{7}{4}\)

\(\left(\frac{4}{5}+\frac{1}{2}\right)\left(\frac{3}{13}-\frac{8}{13}\right)\)

\(=\left(\frac{8}{10}+\frac{5}{10}\right)\cdot\left(-\frac{5}{13}\right)\)

\(=\frac{13}{10}\cdot\left(-\frac{5}{13}\right)=-\frac{1}{2}\)

Answer 2

a,  3x-12 = 30 

=> 3x = 30 + 12

=> 3x = 42 

=> x = 42 : 3  = 14 

Vậy x = 14 

b, \(\frac{2}{3}x+\frac{1}{4}=\frac{7}{12}\)

\(\Rightarrow\frac{2}{3}x=\frac{7}{12}-\frac{1}{4}\)

\(\Rightarrow\frac{2}{3}x=\frac{7}{12}-\frac{3}{12}\)

\(\Rightarrow\frac{2}{3}x=\frac{1}{3}\)

\(\Rightarrow x=\frac{1}{3}\div\frac{2}{3}\Rightarrow\frac{1}{3}\cdot\frac{3}{2}=\frac{1}{2}\)

Vậy x = \(\frac{1}{2}\)

c, 2x² = 32 

=> x² = 32 : 2 

=> x² = 16

=> x² = 4² 

=> x = 4 

Vậy x = 4 

Answer 3

thanhks anh nhé!

Answer 4

thức khuya z 

Answer 5

thức chớ

Answer 6

cái phép tính thứ nhất lm sao đổi ra mẫu 24 đc z anh?

Answer 7

\(=\frac{1}{2}+\frac{5}{6}+\frac{-3}{8}\)

\(=\frac{12}{24}+\frac{20}{24}+\frac{-9}{24}\)

\(=\frac{-23}{24}\)

Answer 8

1/2 + 5/6 - 3/8

= 12/24 + 20/24 - 9/24

= 12 + 20 - 9 / 24

= 23/24

10/15 . 7/4 + 7/4 . 9/15 - 4/15 . 7/4

= 7/4 . ( 10/15 + 9/15 - 4/15 )

= 7/4 . 1 

= 7/4 

                      #Louis

Answer 9

\(\frac{10}{15}.\frac{7}{4}+\frac{7}{4}.\frac{9}{15}-\frac{4}{15}.\frac{7}{4}\)

\(=\frac{7}{4}.\left(\frac{10}{15}+\frac{9}{15}-\frac{4}{15}\right)\)

\(=\frac{7}{4}.1\)

\(=\frac{7}{4}\)

Study well ! >_<

Answer 10

\(\frac{1}{2}+\frac{5}{6}-\frac{3}{8}\)

\(=\frac{12}{24}+\frac{20}{24}-\frac{9}{24}\)

\(=\frac{12+20-9}{24}\)

\(=\frac{23}{24}\)

Study well ! >_<

Answer 11

a) 3x - 12 = 30

    3x         = 30 + 12

    3x         = 42

      x         = 42 : 3

      x          = 14

b) 2x²  = 32

       x²  = 32 : 2

      x² = 16

=> x = 4 hoặc x = -4

      Vậy....

                           #Louis

Answer 12

\(\left(\frac{4}{5}+\frac{1}{2}\right).\left(\frac{3}{13}-\frac{8}{13}\right)\)

\(=\left(\frac{8}{10}+\frac{5}{10}\right).\left(\frac{-5}{13}\right)\)

\(=\frac{13}{10}.\frac{-5}{13}\)

\(=\frac{-5}{10}=\frac{-1}{2}\)

Study well ! >_<

Answer 13

a, 3x - 12 = 30

=> 3x = 30 + 12

=> 3x = 42

=> x = 42 : 3

=> x = 14

Study well ! >_<

Answer 14

rồi rồi thanks các anh chị nhiều

Answer 15

a, x-12=30

=>x=42

c, 2X²=32

=>x²=16

=> x=4 hoặc x=-4