Question

In an A.P if S10=550 and a=100 then value of d is​

Answer 1

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★ Gɪᴠᴇɴ :-

• S₁₀ = 550
• a = 100

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★ Tᴏ Fɪɴᴅ :-

• Common difference ( d ) = ?

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★ Sᴏʟᴜᴛɪᴏɴ :-

As we know that

Sₙ = n/2 [ 2a + ( n - 1 )d ]

Similarly

➨ S₁₀ = n/2 [ 2a + ( n - 1 ) d ]

Substituting

• a = 100
• n = 10
• S₁₀ = 550

➨ S₁₀ = 10/2 [ 2(100) + ( 10 - 1 ) d ]

➨ 550 = 5[ 200 + 9d ]

➨ 550 ÷ 5 = 200 + 9d

➨ 110 - 200 = 9d

➨ - 90 ÷ 9 = d

➨ Common difference ( d ) = - 10

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Hence , common difference ( d ) = - 10

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Answer 2

Answer:

Minus 10 .

Step-by-step explanation:

Sn = 550, a=100, d =?

Sn= n/2(2a+(n-1)d)

550= 10/2 ( 2×100 +( 10-1) d)

550 = 5 (200+9d)

550/5 = 200 + 9d

110 = 200 + 9d

110 - 200 = 9d

-90 = 9d

-90/9 = d

-10 = d

Therefore d= -10.