1-3-2-3-3-3-4-3-x-3-1-4-2-7-3-10-x-3x-1-2021-find-x-

Question Number 150769 by mathdanisur last updated on 15/Aug/21

\frac{1^{3} + 2^{3} + 3^{3} + 4^{3} + \dots + x^{3}}{1 \cdot 4 + 2 \cdot 7 + 3 \cdot 10 + \dots + x (3 x + 1)} = 2021

find x = ?

Answered by nimnim last updated on 15/Aug/21

L e t m e g i v e a t r y . .

\frac{{[\frac{x (x + 1)}{2}]}^{2}}{3 \times \frac{x (x + 1) (2 x + 1)}{6} + \frac{x (x + 1)}{2}} = 2021

\Rightarrow \frac{\frac{x (x + 1)}{2}}{2 x + 1 + 1} = 2021

\Rightarrow \frac{x}{4} = 2021

\Rightarrow x = 8084

Commented by mathdanisur last updated on 15/Aug/21

Thankyou Ser