Функция задана формулой y=-6x+15. Найдите:

Ответ:

а) значение y; если x=-0,5;0;2 1/3;

б) значение x, при котором y=-3;0;20.

\[y = - 6x + 15\]

\[а)\ y;если\ x = - 0,5;0;2\frac{1}{3};\]

\[x = - 0,5:\]

\[y = - 6 \cdot ( - 0,5) + 15 = 3 + 15 = 18.\]

\[x = 0:\]

\[y = - 6 \cdot 0 + 15 = 15.\]

\[x = 2\frac{1}{3} = \frac{7}{3}:\]

\[y = - 6 \cdot \frac{7}{3} + 15 = - 14 + 15 = 1.\]

\[б)\ x,\ при\ котором\ y = - 3;0;20.\]

\[y = - 3:\]

\[- 3 = - 6x + 15\]

\[6x = 15 + 3\]

\[6x = 18\]

\[x = 3.\]

\[y = 0:\]

\[0 = - 6x + 15\]

\[6x = 15\]

\[x = \frac{15}{6} = \frac{5}{2}\]

\[x = 2,5.\]

\[y = 20:\]

\[20 = - 6x + 15\]

\[6x = 15 - 20\]

\[6x = - 5\]

\[x = - \frac{5}{6}.\]