1)240x15-80x6x3-60x4

=240x15-80x3x6-240x1

=240x15-240x6-240x1

=240x(15-6-1)

=240x8

=1920

2)150x5x3x6-15x11

150x5x6x3-15x10-150x0,2

=150x5x6x3-150x1-150x0,2

=150x(5+6+3-1-0,2)

=150x12,8

=1980

cho mình kết bạn với

giúp mình bài này với mình gấp lắm

\(x^2=900\Leftrightarrow x^2=30^2\Rightarrow x=30\)

Chọn A

mik nghĩ A

a) \(\dfrac{6}{13}:\left(\dfrac{1}{2}-x\right)=\dfrac{15}{39}\)

\(\dfrac{1}{2}-x=\dfrac{6}{13}:\dfrac{15}{39}\)

\(\dfrac{1}{2}-x=\dfrac{6}{5}\)

\(x=\dfrac{1}{2}-\dfrac{6}{5}\)

\(x=-\dfrac{7}{10}\)

b) \(3\times\left(\dfrac{x}{4}+\dfrac{x}{28}+\dfrac{x}{70}+\dfrac{x}{130}\right)=\dfrac{60}{13}\)

\(3\times x\times\left(\dfrac{1}{4}+\dfrac{1}{28}+\dfrac{1}{70}+\dfrac{1}{130}\right)=\dfrac{60}{13}\)

\(x\times\left(\dfrac{3}{1\times4}+\dfrac{3}{4\times7}+\dfrac{3}{7\times10}+\dfrac{3}{7\times13}\right)=\dfrac{60}{13}\)

\(x\times\left(1-\dfrac{1}{4}+\dfrac{1}{4}-\dfrac{1}{7}+\dfrac{1}{7}-\dfrac{1}{10}+\dfrac{1}{10}-\dfrac{1}{13}\right)=\dfrac{60}{13}\)

\(x\times\left(1-\dfrac{1}{13}\right)=\dfrac{60}{13}\)

\(x\times\dfrac{12}{13}=\dfrac{60}{13}\)

\(x=\dfrac{60}{13}:\dfrac{12}{13}\)

\(x=5\)

-2x - 40 = (5 - x) - (-15 + 60)

-2x - 40 = (5 - x) - 45

-2x - 40 = -40 - x

-2x - x = 40 - 40

      -3x = 0

         x = 0

2(x - 4) - 3(x + 7) = 14

    2x - 8 - 3x - 21 = 14

                 -x - 29 = 14

                        -x = 14  + 29

                        -x = 43 

                         x = -43

-7(5 - x) - 2(x - 10) = 15

-35 + 7x - 2x + 20 = 15

              -15 + 5x = 15

                       5x = 15 + 15

                       5x = 30

                         x = 6

         \(-2x-40=\left(5-x\right)-\left(-15+60\right)\)

\(\Leftrightarrow\)\(-2x-40=5-x+15-60\)

\(\Leftrightarrow\)\(-2x-40=-x-40\)

\(\Leftrightarrow\)\(-2x+x=40-40\)

\(\Leftrightarrow\)\(x=0\)

Vậy....

\(x+18=2-2x\)

\(2x+x=2-18\)

\(3x=-20\)

\(x=-20:3\)

\(x=\frac{-20}{3}\)

đây là 3 yêu cầu khác nhau à bạn

tự làm đi

a) Ta có: \(\dfrac{x}{-15}=\dfrac{-60}{x}\)

\(\Leftrightarrow x^2=\left(-15\right)\cdot\left(-60\right)=900\)

hay \(x\in\left\{30;-30\right\}\)

Vậy: \(x\in\left\{30;-30\right\}\)

b) Ta có: \(\left|x\right|+0.573=2\)

\(\Leftrightarrow\left|x\right|=1.427\)

hay \(x\in\left\{1.427;-1.427\right\}\)

Vậy: \(x\in\left\{1.427;-1.427\right\}\)

c) Ta có: \(\left|x+\dfrac{1}{3}\right|-4=-1\)

\(\Leftrightarrow\left|x+\dfrac{1}{3}\right|=3\)

\(\Leftrightarrow\left[{}\begin{matrix}x+\dfrac{1}{3}=3\\x+\dfrac{1}{3}=-3\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{8}{3}\\x=-\dfrac{10}{3}\end{matrix}\right.\)

Vậy: \(x\in\left\{\dfrac{8}{3};-\dfrac{10}{3}\right\}\)

d) Ta có: \(0.01:2.5=\left(0.75x\right):0.75\)

\(\Leftrightarrow\dfrac{0.75\cdot x}{0.75}=\dfrac{0.01}{2.5}\)

\(\Leftrightarrow x=\dfrac{1}{250}\)

Vậy: \(x=\dfrac{1}{250}\)

X – 60 : 15 = 20,5

=> X – 60  = 307,5

=> X   = 367,5

 X : 4 + 12 = 23

=>  X : 4 = 11

=>  X  = 44

 ( x – 60 ) : 15 = 20

=> x – 60  =  300

=>  x  =  360

 3 .(x + 7)- 15= 27

=>  3 .(x + 7)  = 42

=>  x + 7  = 14

=>  x  =  7

 2. ( x – 5 )- 17 = 24 + 6 x 1,5

=>  2. ( x – 5 )  - 17  =  33

=>   2. ( x – 5 ) = 50

=>  x - 5  =  25

=>  x  =  30

\(a,x-60:15=20,5\)

\(x-4=20,5\)

\(x=20,5+4=24,5\)

\(b,x:4+12=23\)

\(x:4=23-12=11\)

\(x=11.4=44\)

\(c,\)\(\left(x-60\right)\)\(:15=20\)

\(x-60=20.15=300\)

\(x=300+60=360\)

\(d,3\left(x+7\right)\)\(-15=27\)

\(3\left(x+7\right)\)\(=27+15=42\)

\(x+7=42:3=14\)

\(x=14-7=7\)

\(e,2\left(x-5\right)\)\(-17=24+6.1,5=24+9=33\)

\(2\left(x-5\right)\)\(=33+17=50\)

\(x-5=50:2=25\)

\(x=25+5=30\)

=>........................