Question

in an ap,A10 is equal to 175 and A20 is equal to 475 then find ap​

Answer 1

Question :

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In an AP ${a}_{10} = 175 \:$and ${a}_{20} = 475$then find the AP.

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Answer :

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-95, -65, -35.......

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Explanation :

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Formula :

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${a}_{n} = a + (n - 1)d$

Solution :

${a}_{10} = 175$

(a + 9d) = 175

a = 175 - 9d

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Again

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${a}_{20} = 475$

(a + 19d) = 475

(175 - 9d) + 19d = 475

175 - 9d + 19d = 475

10d = 300

$d = \frac{300}{10}$

d = 30

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a = 175 - 9d

a = 175 - 9(30)

a = 175 - 270

a = -95

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${a}_{2} = - 95 + 1(30) \\ {a}_{2} = - 95 + 30 \\ {a}_{2} = - 65$

${a}_{3} = - 95 + 2(30) \\ {a}_{3} = - 95 + 60 \\ {a}_{3} = - 35$

AP = -95 ,-65 ,-35 .......