algebra easy sequences and series?
a 50 row theater has 40 seats in the front row. the second row has 41 seats. if each row has one more than the row in front of it, how many seats are there in the theater?
a)6450 b)6500 c)3225 d)3250
find the sum of the first 22 terms of the arithemetic progression, if the first term is 4 and the common difference is 4.
a)1012 b)968 c)368 d) 2024
find the sum of the first 16 terms of the arithmetic progression, if the first term is -5 and the common difference is -6
a)-1600 b)-760 c)-800 d)600
please help! i don't understand any of these!!!! :[
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The formula for the sum is (a(1) + a(n)) • (n/2)
So for the first, a(1) = 40, a(50) = 89 and n = 50 so (40 + 89) • 50/2
Then for the second you need the 22nd term.. That formula is a(n) = a(1) + d(n - 1)
so a(22) = 4 + 4(21) = 4 + 84 = 88
Then use the formula from the first question.
And the last one is just like the second one.
hi buddy enable X0 = a a + (ok - a million) 3 = 15 (this could be a formulation) ok - a million = 5 ok = 6 enable Xk+a million = b b + (m - a million) -3 = 0 m - a million = 5 m = 6 n = m + ok = 12 it is arithematic progession (Algebra)