Trả lời

720:[41-(2x-5)]=120

        41-(2x-5)=720:120

       41-(2x-5)=6

             2x-5 =41-6

            2x-5 =35

            2x    =35+5

            2x    =40

          =>x    =40:2

         =>x    =20

Học tốt !

thank lovely(K^-^M) nha

đúng rùi đó

Vá ước của 0 là mấy?

Trả lời

Số 0 không có ước

Và tất cả các số đều là bội của 0

Học tốt !

5x là 5.x hay 5x là 1 số

c)

       Có  Q = P.(x+1) = \(\frac{-3.\left(x+1\right)}{\sqrt{x}-2}\)

\(\Leftrightarrow-Q=\frac{3x+3}{\sqrt{x}-2}=\frac{3x-6\sqrt{x}+6\sqrt{x}+3}{\sqrt{x}-2}=\frac{3\sqrt{x}\left(\sqrt{x}-2\right)+6\left(\sqrt{x}-2\right)+15}{\sqrt{x}-2}\)

\(\Leftrightarrow-Q=3\sqrt{x}+6+\frac{15}{\sqrt{x}-2}\)

\(\Leftrightarrow-Q=3\left(\sqrt{x}-2\right)+\frac{15}{\sqrt{x}-2}+12\)

\(\Leftrightarrow-Q\ge2\sqrt{3\left(\sqrt{x}-2\right).\frac{15}{\sqrt{x}-2}}+12=2\sqrt{45}+12\)

\(\Leftrightarrow-Q\ge6\sqrt{5}+12\)

\(\Leftrightarrow Q\le-6\sqrt{5}-12\)

          Dấu " = " Xảy ra khi :

                                     \(3.\left(\sqrt{x}-2\right)=\frac{15}{\sqrt{x}-2}\Leftrightarrow\left(\sqrt{x}-2\right)^2=5\)

                                     \(\Leftrightarrow\orbr{\begin{cases}\sqrt{x}-2=\sqrt{5}\\\sqrt{x}-2=-\sqrt{5}\end{cases}\Leftrightarrow\orbr{\begin{cases}\sqrt{x}=2+\sqrt{5}\Leftrightarrow x=9+4\sqrt{5}\\\sqrt{x}=2-\sqrt{5}\left(Sai\right)\end{cases}}}\)

Vậy  Max Q = \(-6\sqrt{5}-12\)khi  x = \(9+4\sqrt{5}\)

a ) 9^7 . 9^8 = 9⁷⁺⁸ =9¹⁵

b ) 8^6 : 8^4 = 8^6-4 = 8²

c ) 5^3 . 8^3 = ( 5.8 )³ = 40^3

d ) 24^5 : 6^5 = ( 24:6 )⁵ = 4^5

3* là nhân hử

98 + 3 × ( x + 7 ) = 110

3 × ( x + 7 ) = 110 - 98

3 × ( x + 7 ) = 12

x + 7 = 12 ÷ 3

x + 7 = 4

x = 4 - 7 

x = - 3

Vậy, x = - 3

Cbht

a) (x - 32) = 68

x = 68 + 32

x = 100

b)9 .x+18=274-4

9.x+18=270

9x=270-18

9x=252

x=252:9

x=28

c) 418 - x = 860 - 442

418 - x = 418

x = 0

d) b xem lại câu hỏi nhé

 T.I.C.K GIÚP MK NHÉ!

A> => x=0+68+32

=>x=100

b> =>x=442+418-860=> x=0

c> => 9x=274-4-18

=>9x=252

=> x=28

\(2x+x=\frac{11}{12}\)

\(\Rightarrow x.\left(2+1\right)=\frac{11}{12}\)

\(\Rightarrow x.3=\frac{11}{12}\)

\(\Rightarrow x=\frac{11}{12}:3\)

\(\Rightarrow x=\frac{11}{36}\)

Vậy \(x=\frac{11}{36}\)

Chúc bạn học tốt 

\(2x+x=\frac{11}{12}\)

\(\Leftrightarrow x.\left(2+1\right)=\frac{11}{12}\)

\(\Leftrightarrow x.3=\frac{11}{12}\)

\(\Leftrightarrow x=\frac{11}{12}:3\)

\(\Leftrightarrow x=\frac{11}{12}.\frac{1}{3}\)

\(\Leftrightarrow x=\frac{11}{36}\)

Vậy : \(x=\frac{11}{36}\)

Rất vui vì giúp đc bn !!!

giúp mình ik nhá

\(A=5\left(\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+...+\frac{1}{6480}\right)\)

\(=5\left(\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+...+\frac{1}{80.81}\right)\)

\(=5\left(\frac{2-1}{1.2}+\frac{3-2}{2.3}+\frac{4-3}{3.4}+...+\frac{81-80}{80.81}\right)\)

\(=5\left(1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+...+\frac{1}{80}-\frac{1}{81}\right)\)

\(=5\left(1-\frac{1}{81}\right)=\frac{5.80}{81}=\frac{400}{81}\)

b)

\(B=7\left(\frac{1}{15}+\frac{1}{35}+\frac{1}{63}+...+\frac{1}{483}\right)\)

\(=7.\left(\frac{1}{3.5}+\frac{1}{5.7}+\frac{1}{7.9}+...+\frac{1}{21.23}\right)\)

=> \(2.B=7\left(\frac{2}{3.5}+\frac{2}{5.7}+\frac{2}{7.9}+...+\frac{2}{21.23}\right)\)

\(=7\left(\frac{5-3}{3.5}+\frac{7-5}{5.7}+\frac{9-7}{7.9}+...+\frac{23-21}{21.23}\right)\)

\(=7.\left(\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+\frac{1}{7}-\frac{1}{9}+\frac{1}{21}-\frac{1}{23}\right)\)

\(=7\left(\frac{1}{3}-\frac{1}{23}\right)=\frac{7.20}{69}=\frac{140}{69}\)

=> \(B=\frac{140}{69}:2=\frac{70}{69}\)

a) \(\frac{4}{11}-\frac{7}{15}+\frac{7}{11}-\frac{5}{15}\)

\(=\left(\frac{4}{11}+\frac{7}{11}\right)-\left(\frac{7}{15}+\frac{5}{15}\right)\)

\(=1-\frac{4}{5}\)

\(=\frac{1}{5}\)

b) \(\frac{7}{3}-\frac{4}{9}-\frac{1}{3}-\frac{5}{9}\)

\(=\left(\frac{7}{3}-\frac{1}{3}\right)-\left(\frac{4}{9}+\frac{5}{9}\right)\)

\(=2-1\)

\(=1\)

c) \(\frac{1}{4}+\frac{7}{33}-\frac{5}{3}\)

\(=\frac{-1}{4}+\frac{-16}{11}\)

\(=\frac{-75}{44}\)

d) \(\frac{-3}{4}\times\frac{8}{11}-\frac{3}{11}\times\frac{1}{2}\)

\(=\frac{-6}{11}-\frac{3}{22}\)

\(=\frac{15}{22}\)

e) \(\frac{1}{15}+\frac{1}{35}+\frac{1}{63}+\frac{1}{99}+\frac{1}{143}+\frac{1}{195}\) 

\(=\frac{1}{3\times5}+\frac{1}{5\times7}+\frac{1}{7\times9}+\frac{1}{9\times11}+\frac{1}{11\times13}+\frac{1}{13\times15}\)

\(=\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+\frac{1}{7}-\frac{1}{9}+\frac{1}{9}-\frac{1}{11}+\frac{1}{11}-\frac{1}{13}+\frac{1}{13}-\frac{1}{15}\)

\(=\frac{1}{3}-\frac{1}{15}\)

\(=\frac{4}{15}\)