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}