Question

For a+15d=100,the value of n is ___
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Answer 1

Step-by-step explanation:

Given :-

First term (a) = 15

Common difference (d) = -3

Last term (an) = 0

To Find :-

Number of terms n

Solution :-

an = a + (n - 1 ) d

Putting values

» 0 = 15 + (n - 1)-3

» -15 = -3n + 3

» -15 - 3 = -3n

» -18 = -3n

» -18/-3 = n

» 6 = n

》n = 6

Answer 2

For a+15d=100,the value of n is 16

The given term is the notation of the AP

which can be expressed as

aₙ = a+(n-1)d

where,

• a = first term
• n = number of terms
• d = common difference

if we compare this with the given term we get:

• a+(n-1)d = a+15d
• n-1 = 15
• n = 15+1
• n = 16