Datrys {l}{a_{n}=-3(n-1)/3-2n}{n=4}

$$\left\{ \begin{array} { l } { a _ { n } = - \frac { 3 ( n - 1 ) } { 3 - 2 n } } \\ { n = 4 } \end{array} \right.$$

Datrys ar gyfer a_n, n

$$a_{n} = \frac{9}{5} = 1\frac{4}{5} = 1.8$$

$$n=4$$

Camau Ateb

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

$$a_{n}=-\frac{3\left(4-1\right)}{3-2\times 4}$$

Tynnu 1 o 4 i gael 3.

$$a_{n}=-\frac{3\times 3}{3-2\times 4}$$

Lluosi 3 a 3 i gael 9.

$$a_{n}=-\frac{9}{3-2\times 4}$$

Lluosi -2 a 4 i gael -8.

$$a_{n}=-\frac{9}{3-8}$$

Tynnu 8 o 3 i gael -5.

$$a_{n}=-\frac{9}{-5}$$

Gellir ailysgrifennu \frac{9}{-5} fel -\frac{9}{5} drwy echdynnu’r arwydd negatif.

$$a_{n}=-\left(-\frac{9}{5}\right)$$

Gwrthwyneb -\frac{9}{5} yw \frac{9}{5}.

$$a_{n}=\frac{9}{5}$$

Mae’r system wedi’i datrys nawr.

$$a_{n}=\frac{9}{5} n=4$$