Question

Giải các phương trình:

a)      \( - 6x - 15 = 0\);

b)     \( - \frac{9}{2}x + 21 = 0.\)

Answer 1

a)       

\(\begin{array}{l} - 6x - 15 = 0\\\,\,\,\,\,\,\,\,\, - 6x = 15\\\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,x = 15:\left( { - 6} \right)\\\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,x =  - \frac{5}{2}\end{array}\)

Vậy phương trình có nghiệm \(x =  - \frac{5}{2}\)

b)      

\(\begin{array}{l} - \frac{9}{2}x + 21 = 0\\\,\,\,\,\,\,\,\,\, - \frac{9}{2}x =  - 21\\\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,x = \left( { - 21} \right):\left( { - \frac{9}{2}} \right)\\\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,x = \frac{{14}}{3}\end{array}\)

Vậy phương trình có nghiệm \(x = \frac{{14}}{3}\)