Question

The first term od an AP is 4 and common difference is -3 find the sum of the first 20 terms of AP

Answer 1

Answer:

Step-by-step explanation:

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Answer 2

The correct answer is -490.

Given: First term of AP (a) = 4.

Common difference (d) = -3.

To Find: Sum of first 20 terms of AP.

Solution:

Sum of AP = $\frac{n}{2}(2a+(n-1)d)$

As we have to find sum of 20 terms, n = 20.

Put the values of a, d and n in the formula.

Sum = $\frac{20}{2}(2(4)+(20-1)(-3))$

= 10(8 - 19*3)

= 10(-49)

= -490

Hence, the sum of first 20 terms of AP is -490.

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