For an A.P a=11 and d= 7 Find the sum of first 40term of the A.p

1.	For an A.P a=11 and d= 7 Find the sum of first 40term of the A.p
Answer» ★ GIVEN that, In an AP, a = 11 ; d = 7 ★ To FIND, Sum of first 40 terms if AP. ★ Formula : $\orange{\bigstar}\boxed{\rm{\red{ S_{n} = \cfrac{n}{2}[2a + (n-1) d]}}}\:\orange{\bigstar}$ SUBSTITUTE the VALUES. $\bf\:\implies S_{40} = \cancel{\cfrac{40}{2}} [2(11)+(40-1)7]$ $\bf\:\implies S_{40} =20[22 +(39)7]$ $\bf\:\implies S_{40} =20[22 +273]$ $\bf\:\implies S_{40} =20[295]$ $\bf\:\implies S_{40} = 5900$ $\underline{\boxed{\rm{\purple{\therefore Sum\:of\:first\:40\:terms = 5900.}}}}\:\orange{\bigstar}$

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