Canfod yr nfed term

Weithiau, yn hytrach na chanfod y rhif nesaf mewn dilyniant llinol, efallai fod arnot angen canfod y \({41}^{fed}\) rhif, neu’r \({110}^{fed}\) rhif.

Mae ysgrifennu \({41}\) neu \({110}\) o rifau’n cymryd amser, felly gelli di ddefnyddio rheol gyffredinol.

I ganfod gwerth unrhyw derm mewn dilyniant, defnyddia reol yr \({n}^{fed}\) term.

Question

Beth ydy \({n}^{fed}\) term y dilyniant hwn?

Diagram dilyniant llinol

\({1}^{af}\) = \({5}\) \(({5}\times{1})\); \({2}^{ail}\) = \({10}\) \(({5}\times{2})\); \({3}^{ydd}\) = \({15}\) \(({5}\times{3})\)

Felly yr \({n}^{fed}\) term ydy \({5}\times{n}\) neu \({5n}\)

Er enghraifft, i ganfod y \({10}^{fed}\) term, cyfrifa \({5}\times{10} = {50}\). I ganfod y \({7}^{fed}\) term, cyfrifa \({5}\times{7} = {35}\)

Felly y \({41}^{fed}\) term ydy \({5}\times{41} = {205}\) a’r \({110}^{fed}\) term ydy \({5}\times{110} = {550}\)

Question

Beth ydy \({n}^{fed}\) term a \({10}^{fed}\) term y dilyniant hwn: \({2},~{4},~{6}, ...\) ?

\({n}^{fed}\) term \(= {2n}\)

\({10}^{fed}\) term \(= {20}\). I gyfrifo hyn, \({n} = {10}\), felly \({2n} = {2}\times{10} = {20}\)