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√1³ + 2³ + 3³ + 4³ + 5³ +......+99³ = ?Formula
{k × (k +1)} /2 where k is a last number.
इसे इस प्रकार सॉल्व करें
_______ ______
Q. 1 √(1³ + 2³ ) = √(1 + 8) = √9=3Last No. = 2
Then
= {2 × (2 +1)} /2
= {2 × (3)} /2
= 6 /2
= 3
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Q. 2. √1³ + 2³ + 3³ + 4³ ________________ _____________
√(1³ + 2³ + 3³ + 4³ ) = √(1 + 8 +27+64) = √100 = 10
By formula
Last No. = 4
Then
= {4 × (4 +1)} /2
= {2 × (5)} /2
= 20 /2
= 10
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√1³ + 2³ + 3³ + 4³ + 5³ +......+19³ = ?By formula
Last No. = 19
Then
= {19 × (19 +1)} /2
= {19 × (20)} /2
= 380 /2
= 190
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√1³ + 2³ + 3³ + 4³ + 5³ +......+99³ = ?
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