Question

hi plzz slove the answer of thsi questions plxzzzzzzzzz

Answer 1

Here is your answer but remember this:-

a = first term
l = last term
n = number of terms
d = common difference
Sn = Sum of all term (answer)

Que. 4
i) a = 1
l = 13
d = 2
n = 7
$sn = \frac{n}{2} \times (a + l) \\ = \frac{7}{2} \times (1 + 13) \\ = \frac{7}{2} \times 14 \\ = 7 \times 7 \\ = 49$
Answer is 49.

ii) a = 1
l = 19
n = 10
$sn = \frac{n}{2} \: (a + l) \\ = \frac{10}{2} \times (1 + 19) \\ = 5 \times 20 \\ = 100$
Answer is 100.

iii) a = 1
l = 23
n = 12
$sn = \frac{n}{2} \times (a + l) \\ = \frac{12}{2} \times (1 + 23) \\ = 6 \times 24 \\ = 144$
Answer is 144.

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