Derivatives of Quadratic Polynomials
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Given:f(x) = -4x2 + 10x + 3
Problem:Determine the derivative of f(x) using the definition of a derivative.

f ' (x) = lim
f(x+h) - f(x)
h
h→0

f ' (x) = lim
-4(x+h)2+(x+h)+3 - (-4x2+10x+3)
h
h→0

f ' (x) = lim
-4(x2+xh+h2)+10(x+h)+3 - (-4x2+10x+3)
h
h→0

f ' (x) = lim
-4x2+xh-4h2+10x+10h+3 + x2-10x-3
h
h→0

f ' (x) = lim
xh+h2+h
h
h→0

f ' (x) = lim
h(x+h+)
h
h→0

f ' (x) = limx+h+
h→0

f ' (x) =  x+