the product rule for differentiation. if you had to differentiate f(x) = (3x + 2)(x – 1), how...
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The Product Rule for Differentiation
If you had to differentiate f(x) = (3x + 2)(x – 1), how would you start?
)(' xf
Examine the original function f(x) = (3x + 2)(x – 1)
It is a product of two functions. What are they?
g(x) = and h(x) =
Since f(x) = g(x) h(x) does f /(x) g /(x) h /(x) ?
)(' xg )(' xh
)3)(1()1)(23()(' xxxf
16)(' xxf
We can derive this function another way as shown below. Where do the parts come from?
When we expanded, we determined the derivative to be
To differentiate a function f(x) which is the product of two functions g(x) and h(x) you……
Multiply the first function by the derivative of the second function
then add
The product of the second function and the derivative of the first
If f(x) = g(x)h(x), then
)(' xf
f(x) = g(x)h(x) f /(x) = g(x) h /(x) + h(x) g /(x)
Example 1 Differentiate f(x) = x2 sin x
Let g(x) = and h(x) =
g /(x) = h /(x) =
f /(x) = In its simplest form:
f /(x) =
Example Two - Differentiate
132 2 xxxy
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