Question

15. 5x-15x²= 0
16. 8x2 = 0
17. x²+2x+3=0​

Answer 1

$\displaystyle\bf\\15)\\\\5x-15x^{2} =0 \ |:5\\\\x-3x^{2} =0\\\\x\cdot(1-3x)=0\\\\\\\left[\begin{array}{ccc}x=0\\1-3x=0\end{array}\right\\\\\\\left[\begin{array}{ccc}x=0\\-3x=-1\end{array}\right\\\\\\\left[\begin{array}{ccc}x_{1} =0\\x_{2} =\dfrac{1}{3} \end{array}\right\\\\\\Otv et \ : \ 0 \ \ ; \ \ \frac{1}{3}\\\\\\16)\\\\8x^{2} =0\\\\x^{2} =0\\\\x=0\\\\Otvet \ : \ 0\\\\\\17)\\\\x^{2} +2x+3=0\\\\D=2^{2} -4\cdot 3=4-12=-8 < 0$

Ответ : корней нет