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Let $(f_j)_{j=1}^{\infty}$ be the sequence of Fibonacci numbers. Prove that $$ \sum_{j =1}^k f_j^2 = f_{k}f_{k+1}$$ for all $k \in \mathbb{N}$

If anybody could lend a hand in how to go about starting this proof it would be greatly appreciated. For some reason, I'm lost on breaking apart sums when Fibonacci numbers are involved.

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