find the 20th term of the A.P 80,75,70... calculted the number of terms required to make the sum equal to zero
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80, 75, 70,............
a = 80 , d = -5
20th term = a+(n-1)d = 80+(19)(-5) = 80-95 = -15
If the sum of the terms in the A.p. should be equal to zero, then the last term should be -80
-80 = 80+(n-1)(-5)
160 = (n-1)5
n-1 = 32
n=33
∴ no. of terms= 33
a = 80 , d = -5
20th term = a+(n-1)d = 80+(19)(-5) = 80-95 = -15
If the sum of the terms in the A.p. should be equal to zero, then the last term should be -80
-80 = 80+(n-1)(-5)
160 = (n-1)5
n-1 = 32
n=33
∴ no. of terms= 33
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