Đáp án + Giải thích các bước giải:
$\text{a) ( x - 15 ) : 3 = 19}$
$\text{⇔x - 15 = 57}$
$\text{⇔x = 72}$
$\text{Vậy x = 72}$
$\text{b) 27 - 3( x + 2 ) = 6}$
$\text{⇔3( x + 2 ) = 21}$
$\text{⇔x + 2 = 7}$
$\text{⇔x = 5}$
$\text{Vậy x = 5}$
$\text{c) ( 5x - 45 ). 15 = 450}$
$\text{⇔5x - 45 = 30}$
$\text{⇔5x = 75}$
$\text{⇔x = 15}$
$\text{Vậy x = 15}$
$\text{d) 70 - 5( x - 3 ) = 45}$
$\text{⇔5( x - 3 ) = 25}$
$\text{⇔x - 3 = 5}$
$\text{⇔x = 8}$
$\text{Vậy x = 8}$
$\text{e) 187 - 3( x + 4 ) = 34}$
$\text{⇔3( x + 4 ) = 153}$
$\text{⇔x + 3 = 51}$
$\text{⇔x = 48}$
$\text{Vậy x = 48}$
$\text{g) 440 + 2( 125 - x ) = 546}$
$\text{⇔2( 125 - x ) = 106}$
$\text{⇔125 - x = 53}$
$\text{⇔x = 72}$
$\text{Vậy x = 72}$
$\text{h) ( x - 15 ) : 5 + 20 = 22}$
$\text{⇔( x - 15 ) : 5 = 2}$
$\text{⇔x - 15 = 20}$
$\text{⇔x = 35}$
$\text{Vậy x = 35}$
$\text{i) 231 - ( x - 6 )= 1339 : 13}$
$\text{⇔231 - ( x - 6 ) = 103}$
$\text{⇔x - 6 = 128}$
$\text{⇔x = 134}$
$\text{Vậy x = 134}$
$\text{k) x( 3x - 9 ) = 0}$
$⇔$\(\left[ \begin{array}{l}x= 0\\x=3x - 9 = 0\end{array} \right.\)
$⇔$\(\left[ \begin{array}{l}x= 0\\x=3x = 9\end{array} \right.\)
$⇔$\(\left[ \begin{array}{l}x= 0\\x = 3\end{array} \right.\)
$Vậy$ \(\left[ \begin{array}{l}x= 0\\x = 3\end{array} \right.\)
$\text{l) ( 3x - 5 )x( 2x - 16 ) = 0}$
$⇔$\(\left[ \begin{array}{l}3x - 5 = 0\\x = 0\\2x - 16 = 0\end{array} \right.\)
$⇔$\(\left[ \begin{array}{l}3x = 5\\x = 0\\2x = 16\end{array} \right.\)
$⇔$\(\left[ \begin{array}{l} x = \dfrac{5}{3}\\x = 0\\x = 4\end{array} \right.\)
$Vậy$ \(\left[ \begin{array}{l} x = \dfrac{5}{3}\\x = 0\\x = 4\end{array} \right.\)
$\text{m) x+(x+1)+(x+2) + ... +( x+100) = 10100}$
$\text{⇔x + x + 1 + x + 2 + ... + x + 100 = 10100}$
$\text{⇔( x + x + ... + x ) + ( 1 + 2 + ... + 100 ) = 10100}$
$\text{⇔101x + 5050 = 10100}$
$\text{⇔101x = 5050}$
$\text{⇔x = 50}$
$\text{Vậy x = 50}$
$\text{n) 3( x - 5 ) = x + 7}$
$\text{⇔3x - 15 = x + 7}$
$\text{⇔2x = 22}$
$\text{⇔x = 11}$
$\text{⇔Vậy x = 11}$
Cho mình xin câu trả lời hay nhất nha!
