\(2.3^x-4=50\)

\(\Rightarrow2.3^x=54\Rightarrow3^x=27=3^3\)

\(\Rightarrow x=3\)

biết làm rồi thì giúp gì

240

a)240

b)12; 24; 36; 48

( 1 + x ) + ( 2 + x ) + ( 3 + x ) + ...+ ( 100 + x ) = 2018

\(\Rightarrow\)( 1 + 2 + 3 + ... + 100 ) + ( x + x + x + ... + x ) = 2018

\(\Rightarrow\){( 1 + 100 ) . [( 100 - 1 ) : 1 + 1 ] : 2 } + ( x + x + ... + x ) = 2018

\(\Rightarrow\)5050 + x . 100 = 2018

\(\Rightarrow\)  x100 = 2018 - 5050 = -3032

\(\Rightarrow\)x = -3032 : 100 = -30,32

vậy x = -30,32

mà nè sai thì xin lỗi đề hơi có vấn đề nếu sai thì sorry nha !!!

\(A=3^x+3^{x+1}+...+3^{x+100}\)

=>\(3A=3^{x+1}+3^{x+2}+...+3^{x+101}\)

=>\(2A=3^{x+101}-3^x\)

=>\(A=\dfrac{3^{x+101}-3^x}{2}\)

=>\(3^{x+101}-3^x=3^{105}-3^4\)

=>x=4

x=4

`@` `\text {Ans}`

`\downarrow`

\(\left(1-\dfrac{1}{2}\right)\times\left(1-\dfrac{1}{3}\right)\times\left(1-\dfrac{1}{4}\right)\times\left(1-\dfrac{1}{5}\right)...\left(1-\dfrac{1}{1000}\right)\)

`=`\(\left(\dfrac{2}{2}-\dfrac{1}{2}\right)\times\left(\dfrac{3}{3}-\dfrac{1}{3}\right)\times\left(\dfrac{4}{4}-\dfrac{1}{4}\right)...\left(\dfrac{1000}{1000}-\dfrac{1}{1000}\right)\)

`=`\(\dfrac{1}{2}\times\dfrac{2}{3}\times\dfrac{3}{4}\times...\times\dfrac{999}{1000}\)

`=`\(\dfrac{1}{1000}\)

\(=\dfrac{1}{2}.\dfrac{2}{3}.\dfrac{3}{4}.\dfrac{4}{5}.......\dfrac{99}{100}=\dfrac{1}{100}\)

1) (X-6)x(2x - 6)=0

=> X - 6 = 0 => x = 0 + 6 = 6

=> 2x - 6 = 0 => 2x = 6 => X = 6 : 2 = 3

Vẫy x{6; 3}

2) 100:(x-7)=1

            x-7 = 100:1

            x-7 = 100

            x   = 100 + 7

            x   = 107