Réitigh {l}{f(x)=-x^2+3x+5}{x=-3/5}

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

Réitigh do f,x.

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

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

Céimeanna Réitigh

Cuir an chéad cothromóid san áireamh. Ionsáigh luachanna aitheanta na n-athróg sa chothromóid.

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

Ríomh cumhacht -\frac{3}{5} de 2 agus faigh \frac{9}{25}.

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

Méadaigh 3 agus -\frac{3}{5} chun -\frac{9}{5} a fháil.

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

Dealaigh \frac{9}{5} ó -\frac{9}{25} chun -\frac{54}{25} a fháil.

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

Suimigh -\frac{54}{25} agus 5 chun \frac{71}{25} a fháil.

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

Iolraigh an dá thaobh faoi -\frac{5}{3}, an deilín de -\frac{3}{5}.

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

Méadaigh \frac{71}{25} agus -\frac{5}{3} chun -\frac{71}{15} a fháil.

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

Tá an córas réitithe anois.

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