Datrys {l}{f(x)=-x^2+3x+5}{x=-3/5}

$$\left. \begin{array} { l } { f ( x ) = - x ^ { 2 } + 3 x + 5 } \\ { x = - \frac { 3 } { 5 } } \end{array} \right.$$

Datrys ar gyfer f, x

$$x=-\frac{3}{5}=-0.6$$

$$f = -\frac{71}{15} = -4\frac{11}{15} \approx -4.733333333$$

Camau Ateb

Ystyriwch yr hafaliad cyntaf. Mewnosod y gwerthoedd sy’n hysbys i’r hafaliad.

$$f\left(-\frac{3}{5}\right)=-\left(-\frac{3}{5}\right)^{2}+3\left(-\frac{3}{5}\right)+5$$

Cyfrifo -\frac{3}{5} i bŵer 2 a chael \frac{9}{25}.

$$f\left(-\frac{3}{5}\right)=-\frac{9}{25}+3\left(-\frac{3}{5}\right)+5$$

Lluosi 3 a -\frac{3}{5} i gael -\frac{9}{5}.

$$f\left(-\frac{3}{5}\right)=-\frac{9}{25}-\frac{9}{5}+5$$

Tynnu \frac{9}{5} o -\frac{9}{25} i gael -\frac{54}{25}.

$$f\left(-\frac{3}{5}\right)=-\frac{54}{25}+5$$

Adio -\frac{54}{25} a 5 i gael \frac{71}{25}.

$$f\left(-\frac{3}{5}\right)=\frac{71}{25}$$

Lluoswch y ddwy ochr â -\frac{5}{3}, cilyddol -\frac{3}{5}.

$$f=\frac{71}{25}\left(-\frac{5}{3}\right)$$

Lluosi \frac{71}{25} a -\frac{5}{3} i gael -\frac{71}{15}.

$$f=-\frac{71}{15}$$

Mae’r system wedi’i datrys nawr.

$$f=-\frac{71}{15} x=-\frac{3}{5}$$