câu 1:

a) 500-(300)-190+(-210)

= 500-300-190-210

= 200 - 210 -190

=-10 - 190

=-200

b) (-3)³ .5+12.(-6)

= -27.5 -72

=-135 - 72

=-207

c) 15.(-19-4)-19.(15-4)

= 15.(-23) - 19.11

=-345 - 209

=-554

câu 2: tìm x thuộc Z

a) 3x-2=3

=> 3x=3/2

=> x=1/2

b) x chia hết cho 5 và -7<x<11

=> x thuộc {-5;0;5;10}

Câu 1: 

a) Ta có: \(500-\left(300\right)-190+\left(-210\right)\)

\(=500-300-190-210\)

\(=\left(500-300\right)-\left(190+210\right)\)

\(=200-400=-200\)

b) Ta có: \(\left(-3\right)^3\cdot5+12\cdot\left(-6\right)\)

\(=\left(-3\right)^3\cdot5-3\cdot4\cdot3\cdot2\)

\(=-5\cdot3^3-3^2\cdot8\)

\(=3^2\cdot\left(-5\cdot3-8\right)\)

\(=9\cdot\left(-15-8\right)=9\cdot\left(-23\right)=-207\)

c) Ta có: \(15\cdot\left(-19-4\right)-19\cdot\left(15-4\right)\)

\(=-15\cdot19-15\cdot4-15\cdot19+19\cdot4\)

\(=-30\cdot19+4\cdot4\)

\(=-2\cdot\left(15\cdot19+2\cdot4\right)\)

\(=-2\cdot\left(285+8\right)=-586\)

\(a,2^{x+1}=3^y=12^x\Rightarrow2^{x+1}.3^y=2^{2x}.3y\)

\(\Rightarrow\frac{2^x}{2^{x+1}}=\frac{3^y}{3^x}\Rightarrow2^{2-x-x-1}=3^{y-x}\)

a) 2² ( x + 3² ) - 5 = 55

=>4(x+9)-5=55

=>4(x+9)=60

=>x+9=15

=>x=6

b)7 ( x + 5² ) - 20 = 190

=>7(x+25)=210

=>x+25=30

=>x=5

c)6 ( x + 2³ ) + 40 = 100

=>6(x+8)+40=100

=>6(x+8)=60

=>x+8=10

=>x=2

a)6

b)5

c)2

6;5;2

Ai làm ơn trả lời hộ mình với đảm bảo mk sẽ cho

\(\frac{x}{2}=\frac{y}{2}=\frac{z}{5}\Rightarrow\frac{x^2}{4}=\frac{y^2}{4}=\frac{z^5}{3125}\)

Áp dụng tính chất của dãy tỉ số bằng nhau ta có:

\(\frac{x^2}{4}=\frac{y^2}{4}=\frac{z^5}{3125}=\frac{x^2+y^2+z^5}{4+4+3125}=\frac{190}{3133}\)

Đến đây thì dễ rồi, bạn tự suy ra x²,y²,z² nhé, rồi suy ra x,y,z là xong

bn trà my làm toi k = 190/3133 đúng rui , còn lại

x/2 =190/3133

x = 380/3133

y/2 = 190/3133

y = 380/3133

z/5 =190/3133

z = 950/3133

a)\(280-\left(x-140\right):35=270\)

\(\Leftrightarrow\left(x-140\right):35=10\)

\(\Leftrightarrow x-140=350\)

\(\Leftrightarrow x=490\)

b) \(\left(190-2x\right):35-32=16\)

\(\Leftrightarrow\left(190-2x\right):35=48\)

\(\Leftrightarrow190-2x=1680\)

\(\Leftrightarrow2x=-1490\Leftrightarrow x=-745\)

c) \(720:\left[41-\left(2x-5\right)\right]=2^3.5\)

\(\Leftrightarrow720:\left[41-\left(2x-5\right)\right]=40\)

\(\Leftrightarrow41-\left(2x-5\right)=18\)

\(\Leftrightarrow2x-5=23\)

\(\Leftrightarrow2x=28\Leftrightarrow x=14\)

280-(x-140):35=270

(x-140):35=280-270

(x-140):35=10

(x-140)=10×35

(x-140)=350

x=350-140

x=210

vậy x=210

(192-2x):35-32=16

(192-2x):35=16+32

(192-2x):35=48

(192-2x)=48×35

(192-2x)=1680

2x=192-1680

2x=-1488

x=-1488:2

x=-744

vậy x=-744

Làm:

a,280-(x-140):35=270

          (x-140):35=280-270

          (x-140):35=10

           x-140       =10.35

           x-140       =350

           x               =350+140

           x               =490

b,(190-2x):35-32=16

   (190-2x):35      =16+32

   (190-2x):35      =48

    190-2x             =48.35

    190-2x             =1680

           2x             =190-1680

           2x              =-1490

             x              =-1490:2 

             x              =-745

c,720:[41-(2x-5)]=2^3.5

   720:[41-(2x-5)]=8.5

   720:[41-(2x-5)]=40

           41-(2x-5)  =720:40

           41-(2x-5)  =18

                  2x-5   =41-18

                  2x-5   =23

                  2x       =23+5

                  2x        =28

                    x         =28:2 

                    x          =14

Bài 1: 

a) Ta có: \(\dfrac{17}{6}-x\left(x-\dfrac{7}{6}\right)=\dfrac{7}{4}\)

\(\Leftrightarrow\dfrac{17}{6}-x^2+\dfrac{7}{6}x-\dfrac{7}{4}=0\)

\(\Leftrightarrow-x^2+\dfrac{7}{6}x+\dfrac{13}{12}=0\)

\(\Leftrightarrow-12x^2+14x+13=0\)

\(\Delta=14^2-4\cdot\left(-12\right)\cdot13=196+624=820\)

Vì Δ>0 nên phương trình có hai nghiệm phân biệt là:

\(\left\{{}\begin{matrix}x_1=\dfrac{14-2\sqrt{205}}{-24}=\dfrac{-7+\sqrt{205}}{12}\\x_2=\dfrac{14+2\sqrt{2015}}{-24}=\dfrac{-7-\sqrt{205}}{12}\end{matrix}\right.\)

b) Ta có: \(\dfrac{3}{35}-\left(\dfrac{3}{5}-x\right)=\dfrac{2}{7}\)

\(\Leftrightarrow\dfrac{3}{5}-x=\dfrac{3}{35}-\dfrac{10}{35}=\dfrac{-7}{35}=\dfrac{-1}{5}\)

hay \(x=\dfrac{3}{5}-\dfrac{-1}{5}=\dfrac{3}{5}+\dfrac{1}{5}=\dfrac{4}{5}\)

ai giúp mik vs

Bài 3: 

a) Ta có: \(2x-3=x+\dfrac{1}{2}\)

\(\Leftrightarrow2x-x=\dfrac{1}{2}+3\)

\(\Leftrightarrow x=\dfrac{7}{2}\)

b) Ta có: \(4x-\left(x+\dfrac{1}{2}\right)=2x-\left(\dfrac{1}{2}-5\right)\)

\(\Leftrightarrow3x-\dfrac{1}{2}-2x+\dfrac{1}{2}-5=0\)

\(\Leftrightarrow x=5\)

Đề:......

<=> 7. (x + 25) = 210

<=> x + 25 = 210 : 7

<=> x + 25 = 30

<=> x = 5

Vậy x = 5

a)\(27.65+27.35+300=27.\left(65+35\right)+300\)

\(=27.100+300=2700+300=3000\)

b)\(3838:\left[\left(190-6.5^2\right):4+3\right]\)

\(=3838:\left[\left(190-6.25\right):4+3\right]\)

\(=3838:\left[\left(190-150\right):4+3\right]\)

\(=3838:\left[40:4+3\right]=3838:\left[10+3\right]\)

\(=3838:13=\dfrac{3838}{13}\)

c)\(2022-x=2021\)

\(x=2022-2021=1\)

d)\(26+14:\left(x-5\right)=33\)

\(14:\left(x-5\right)=33-26=7\)

\(x-5=14+7=2\)

\(x=2+5=7\)

e)đề hỏi làm j thế bạn