5. The sum of the cubes of the first n natural numbers is 2025, then find the value of n.
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Step-by-step explanation:
sn=2025,a=1,d=7.
sn=n/2(2a+(n-1) d)
2025=n/2(2(1)+(n+1)7)
2025=n/2(2+7n+7)
2025×2=n(2+7n+7)
2025×2=2n+7n2+7n
2025×2=9n+7n2
4050=7n2+9n
7n2+9n-4050=0
if you simplify like dis
lastly u can get d answer
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