how can we differentiate

x.(18-2x)

x.(18-2x) can be written as 18x-2x^{2}

now,differentiating 18-2x^{2} w.r.t x

by using chain rule,

d/dx (18x) - d/dx (2x^{2})

18-4x ( x^{n} on differentiation gives nx^{n-1})

so the answer is 18-4x........

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