Tìm x : a. x x 45 + x x 55 = 1000 b. 6/x + 1/2 =2

* Hướng dẫn giải

a. x x 45 + x x 55 = 1000

x  x (45 + 55) = 1000

x x 100 = 1000

x = 1000 : 100

x =  10

b. 

$$\begin{gathered} \frac{6}{x}+\frac{1}{2}=2 \\ 6 : x+\frac{1}{2}= 2 \\ 6 : x = 2-\frac{1}{2} \\ 6 : x = \frac{3}{2} \\ x = 6 : \frac{3}{2} \\ x = 4 \end{gathered}$$