bn lớp mấy vậy

a) 3.x + 30 = (-3)²

   3.x + 30 = 9

           3.x = 9 - 30

           3.x = -21

              x = -21 : 3

              x = -7

b) 171 - 5(x + 7) = 236

            5(x + 7) = 171 - 236

            5(x + 7) = -65

                x + 7 = -65 : 5

                x + 7 = -13

                      x = -13 - 7

                      x = -20

c) -14 - (1 - 4x) = -7

             1 - 4x = -14 - (-7)

             1 - 4x = -7

                  4x = 1 + 7

                  4x = 8

                   x = 2

mik nhah nhất đó

k mik nha

a) 3 . x + 30 = (-3)²

3 . x + 30 = 9

3 . x = 9 - 30

3 . x = 21

x = 21 : 3

x = 7

b) 171 - 5(x + 7) = 236

5(x + 7) = 236 - 171

5(x + 7) = 65

x + 7 = 65 : 5

x + 7 = 13

x = 13 - 7

x = 5

c) -14 - (1 - 4x) = -7

1 - 4x = -14 - (-7)

1 - 4x = -7

4x = 1 - (-7)

4x = 8

x = 8 : 4

x = 2

a)3x+30=(-3)^2

   3x+30=9

   3x     =9-30

   3x     = -21

     x     = -21/3

     x     = -7

b)171-5(x+7)=236

         5(x+7)=171-236

         5(x+7)= -65

            x+7 = -65/5

            x+7 = -13

            x     = -13-7

            x     = 6

c)-14-(1-4x)= -7

          1-4x = -14-(-7)

          1-4x = -7

             4x = 1-(-7)

             4x =8

               x =8:4

               x =2 

(sai cx k bn nha ^^)

a) \(\left(x-3\right)^2-4=0\)

\(\left(x-7\right)\left(x+1\right)=0\)

\(\orbr{\begin{cases}x=7\\x=-1\end{cases}}\)

b) \(x^2-2x=24\)

\(x^2-2x-24=0\)

\(\left(x-6\right)\left(x+4\right)=0\)

\(\orbr{\begin{cases}x=6\\x=-4\end{cases}}\)

c) \(\left(2x-1\right)^2+\left(x+3\right)^2-5\left(x+7\right)\left(x-7\right)=0\)

\(4x^2+4x+1+x^2+6x+9-5\left(x^2-49\right)=0\)

\(5x^2+10x+10-5x^2+245=0\)

\(10x+255=0\)

\(x=-25.5\)

A) \(\left(x-3\right)^2-4=0\)

\(\left(x-3\right)^2=4\Rightarrow\left(x-3\right)^2=\left(-2\right)^2;2^2\)

th1\(\left(x-3\right)^2=2^2\)

\(\Rightarrow x-3=2\)

\(\Rightarrow x=2+3\)

\(\Rightarrow x=5\)

th2: \(\left(x-3\right)^2=\left(-2\right)^2\)

\(\Rightarrow x-3=-2\)

\(\Rightarrow x=-2+3\)

\(\Rightarrow x=1\)

\(\Leftrightarrow x\in\left\{1;5\right\}\)

a) \(\left(x-3\right)^2-4=0\)

Ta xét 2TH:

TH1: \(x-3=2\)

\(x-3+3=2+3\)

\(x=5\)

TH2: \(x-3=-2\)

\(x-3+3=-2+3\)

\(x=1\)

=> \(x\in\left\{1;5\right\}\)

\(\frac{4}{5}\)+ \(\frac{1}{5}\): \(\frac{-2}{15}\)= \(\frac{4}{5}\)+ \(\frac{1}{5}\)* \(\frac{-15}{2}\)=\(\frac{4}{5}\) + \(\frac{-3}{2}\)= \(\frac{-7}{10}\)

b = \(\frac{-7}{12}\). (\(\frac{3}{11}\)+ \(\frac{-14}{11}\)) + \(\frac{5}{6}\)= \(\frac{-7}{12}\). (-1) + \(\frac{5}{6}\)= \(\frac{7}{12}\)+ \(\frac{10}{12}\)= \(\frac{17}{12}\)

x-\(\frac{3}{5}\)x = \(\frac{2}{5}\)

=> x.(1-\(\frac{3}{5}\)) =\(\frac{2}{5}\)

=> x. \(\frac{2}{5}\)= \(\frac{2}{5}\)

=> x=1

Vậy x=1

aを見つける= 175度はどれくらい尋ねるaを見つける= 175度はどれくらい尋ねる

b. \(4x^2+4x-7=0\)

\(\Leftrightarrow\left(2x\right)^2+2.2x+1-8=0\)

\(\Leftrightarrow\left(2x+1\right)^2-8=0\)

\(\Leftrightarrow\left(2x+1-\sqrt{8}\right)\left(2x+1+\sqrt{8}\right)=0\)

\(\Leftrightarrow\orbr{\begin{cases}2x+1-\sqrt{8}=0\\2x+1+\sqrt{8}=0\end{cases}}\Leftrightarrow\orbr{\begin{cases}x=\frac{\sqrt{8}-1}{2}\\x=\frac{-\sqrt{8}-1}{2}\end{cases}}\)

k mình nha bn <3 thanks nhìu hen

\(bn\)\(xem\)\(lai\)\(giup\)\(mk\)\(cho\)\(\frac{x+522}{7}\)\(neu\)\(thay\)\(bang\)\(\frac{x+552}{7}\)\(thi\)\(dug\)\(hon\)

thế thì bạn giải thử xem cô t ra đề thế mà ừ thì cứ cho là x + 552 cx đc

a ) Ta có : - 12 . ( x - 5 ) + 7( 3 - x ) = 5

Suy ra - 12x - ( - 12 ) . 5 + 7 . 3 - 7x = 5

Suy ra - 12x + 60 + 21 - 7x = 5

Suy ra - 12x - 7x = 5 - 60 - 21

Suy ra - 19x = - 76

Suy ra x = -76 : ( - 19 )

Vậy x = 4

b ) Ta có : 30 . ( x + 2 ) - 6  . ( x - 5 ) - 24x = 100

Suy ra 30x + 30 . 2 - 6x - ( - 6 ) . 5 - 24x = 100

Suy ra 30x + 60 - 6x + 30 - 24x = 100

Suy ra 30x - 6x - 24x = 100 - 60 - 30

Suy ra 0x = 10

Vậy x = 0

Mọi người giúp với ạ

a)7^2x33+7^2x67

=7^2x(33+67)

=49x100

=4900

b)490-{[(128+22):3x2^2]-7}

=490-{[150:3x4]-7}

=490-{[50x4]-7}

=490-{200-7}

=490-193

=297