Tìm x, biết: a) x:2,2 = 57,4 - 27;
Giải thích
a) \[x:2,2 = 57,4 - 27\] \[x:2,2 = 30,4\] \[x = 30,4.2,2\] \[x = 66,88\] Vậy \[x = 66,88\].
| b) \(3.{\left( {x - \frac{1}{4}} \right)^2} = \frac{{27}}{4}\) \({\left( {x - \frac{1}{4}} \right)^2} = \frac{{27}}{4}:3 = \frac{9}{4}\) \({\left( {x - \frac{1}{4}} \right)^2} = {\left( {\frac{3}{2}} \right)^2} = {\left( { - \frac{3}{2}} \right)^2}\) | |
Trường hợp 1: \(x - \frac{1}{4} = \frac{3}{2}\) \(x = \frac{3}{2} + \frac{1}{4}\) \(x = \frac{7}{4}\) Vậy \[x \in \left\{ {\frac{7}{4}; - \frac{5}{4}} \right\}\]. | Trường hợp 2: \(x - \frac{1}{4} = - \frac{3}{2}\) \(x = - \frac{3}{2} + \frac{1}{4}\) \(x = - \frac{5}{4}\) | |