d)1990⁰+(x-15)=3¹⁹⁹:3¹⁹⁶-1²⁰⁰⁰

   1+(x-15)=26

        x-15=26-1=25

        x=25+15=40

c) (90:15)²+x=2⁶-2^2.7

   36+x=-16320

         x=-16320-36=-16356

b) (2^x+1)³=125

    (2^x+1)³=5³

    2^x+1=5

    2^x=5-1=4=2²

   x=2

a) ko hiểu đề bài

a) \(3.2^x-3=45\)

\(3\left(2^x-1\right)=45\)

\(2^x-1=15\)

\(2^x=15+1\)

\(2^x=16\)

\(2^x=2^4\)

=>x=4

b) \(\left(2^x+1\right)^3=125\)

\(\left(2^x+1\right)^3=5^3\)

=> \(2^x+1=5\)

Làm tương tự câu a, đc x = 2

c) \(\left(90:15\right)^2+x=2^6-2^{2.7}\)

\(6^2+x=64-16384\)

\(x=-16320-36\)

x=-16356

d) \(1990^0+\left(x-15\right)=3^{199}:3^{196}-1^{2000}\)

1 + x - 15 = 3³-1

x= 27-1-1+15

x=40

a) \(\frac{7}{13}x\frac{7}{15}-\frac{5}{12}x\frac{21}{39}+\frac{49}{91}x\frac{8}{15}=\frac{7}{13}x\frac{7}{15}-\frac{5}{12}x\frac{7}{13}+\frac{7}{13}x\frac{8}{15}\)

\(=\frac{7}{13}x\left(\frac{7}{15}-\frac{5}{12}+\frac{8}{15}\right)=\frac{7}{13}x\left(1-\frac{5}{12}\right)=\frac{7}{13}x\frac{7}{12}=\frac{49}{156}\)

b) \(\left(\frac{12}{199}+\frac{23}{200}-\frac{34}{201}\right)x\left(\frac{1}{2}-\frac{1}{3}-\frac{1}{6}\right)=\left(\frac{12}{199}+\frac{23}{200}-\frac{34}{201}\right)x0=0\)

Bài 2:

a) \(0,5+\left(x-\frac{15}{2}\right):\frac{1}{2}=\frac{9}{2}\)

\(\left(x-\frac{15}{2}\right):\frac{1}{2}=4\)

\(x-\frac{15}{2}=2\) 

x = 19/2

b) \(2012\times x-2010\times x=2014\)

\(x\times\left(2012-2010\right)=2014\)

\(x\times2=2014\)

x = 1007

c) ( x + 1) + (x+2) + (x+3)+...+(x+100) = 5750

\(x\times100+\left(1+2+3+...+100\right)=5750\)

\(x\times100+5050=5750\)

\(x\times100=700\)

x = 7

( 15 - x ) + ( x - 12 ) = ( -5 + x )

( 15 - 12 ) - x + x = -5 + x

3 = -5 + x

x = 3 + 5

x = 8

(x+1)+(x+3)+(x+5)+...+(x+99)=0

( x + x + x + .... + x ) + ( 1 + 3 + 5 + ... + 99 ) = 0

50x + 2500 = 0

50x = -2500

x = -2500 : 50

x = -50

trả lời hết lun đi

mà đây là môn toán mà

\(\dfrac{4}{6}-\dfrac{3}{5}=\dfrac{2}{3}-\dfrac{3}{5}=\dfrac{1}{15}\\ x=\dfrac{2}{3}-\dfrac{8}{21}=\dfrac{2}{7}\\ x=\dfrac{6}{7}\times\dfrac{1}{7}=\dfrac{6}{49}\\ 2-x=\dfrac{7}{9}\\ x=2-\dfrac{7}{9}=\dfrac{11}{9}\)

\(a,\dfrac{4}{6}-\left(\dfrac{6}{15}+\dfrac{1}{5}\right)=\dfrac{4}{6}-\dfrac{3}{5}=\dfrac{1}{15}\)

\(b,x=\dfrac{2}{3}-\dfrac{8}{21}\)

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

\(c,x=\dfrac{6}{7}\times\dfrac{1}{7}\)

\(x=\dfrac{6}{49}\)

\(d,2-x=\dfrac{7}{9}\)

\(x=2-\dfrac{7}{9}\)

\(x=\dfrac{11}{9}\)

1) 5.( x - 6 ) - 2.( x + 9 ) = 21

           5x - 30 - 2x - 18 = 21

                        3x - 48 = 21

                               3x = 21 + 48

                               3x = 69

                                 x = 23

2) 2.( x + 3 ) + 3.( x +  1 ) = 15 - ( - 9 )

               2x + 6 + 3x + 3 = 24

                            5x + 9 = 24

                                  5x = 24 - 9 

                                  5x = 15

                                   x = 3

3) ( - x + 5 ).(3 - x ) = 0

=> - x + 5 = 0 hoặc 3 - x = 0

=> x = 5 hoặc x = 3

4) ( x - 12 ) - 15 = ( 20 - 7 ) - ( 18 + x )

        x - 12 - 15 = 13 - 18 - x 

               x - 27 = - 5 - x 

                x + x = - 5 + 27

                     2x = 22

                       x = 11

5) x - ( 17 - 8 ) = 5 + ( 10 - 3x )

               x - 9 = 5 + 10 - 3x

            x + 3x = 15 + 9

                  4x = 24

                    x = 6

a) Ta có : ( x + 1 ).( 3 - x ) > 0

Th1 : \(\hept{\begin{cases}x+1>0\\3-x>0\end{cases}\Rightarrow\hept{\begin{cases}x>-1\\x>3\end{cases}\Rightarrow}x>3}\)

Th2 : \(\hept{\begin{cases}x+1< 0\\3-x< 0\end{cases}\Rightarrow\hept{\begin{cases}x< -1\\x< 3\end{cases}\Rightarrow}x< -1}\)

sao ko ai làm giúp mk vậy

câu f là 9+3x hay 9-3x vậy???