` a_12 =37 ` और `d=3` दिया है| a और `s_12` ज्ञात कीजिए| एक `A.P.` मैं,

Explanation

`" "d= 3 `
तथा ` " " a_12 =37 " " rArr " " a+ (12 -1)d=37`
`rArr a+ 11xx 3=37`
` rArr " " a=37 -33 =4`
तथा ` " " S_n =(n)/(2) [2a +(n-1) d]` से
` " " S_12 =(12)/(2) [2xx 4+ (12-1) xx3]`
` " " = 6[8+ 33] =6xx 41 =246 `
` therefore " " a= 4,S_12 =246`