Question

find the sum of the first 10terms of an A.P.3, 15, 27, 30.....​

Answer 1

Given:-

➜A=3

➜d=12[15-3]

$\rule{200}{1}$

To Find:-

✪The Sum of first 10terms?

$\rule{200}{1}$

AnsWer:-

☞Sum of first 10 terms is 570.

$\rule{200}{1}$

Formula:-

➜Sⁿ=$\frac{n}{2}$×[2a+(n-1)d]

↝S¹⁰=$\frac{\cancel{10}}{\cancel{2}}$×[2×3+(10-1)×12]

↝S¹⁰=5×[6+108]

↝S¹⁰=5×114

↝S¹⁰=570

$\rule{200}{2}$

Answer 2

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$\huge\tt{GIVEN:}$

• A = 3
• D = 12(15-3)

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$\huge\tt{TO~FIND:}$

• Sum of first 10 terms.

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$\huge\tt{SOLUTION:}$

↪Sⁿ = n/2 × [2a + ( n-1 ) d ]

↪S^10 = 10/2 × [2×3+(10-1)×12]

↪S^10 = 5 × [6+108]

↪S^10 = 5 × 114

↪S^ 10 = 570

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