Using the chain rule, we differentiate both sides of F(G(x)) = x^2 with respect to x, to get

F'(G(x)) * G'(x) = 2x.

Substituting x=1 yields F'(G(1)) * G'(1) = 2. Since G'(1) = 5, F'(G(1)) = 2/5.

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