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New poster

Post Number: 1
Posted on Tuesday, 10 January, 2012 - 02:45 pm:   

I do not know how to expand a bracket in the form (ax + lnbx)^2.
A practice question in my book reads: The point P lies on the curve with equation y=(3x + ln2x)^2. The x-coordinate of P is 0.5. Find an equation of the tangent to the curve at the point P.
I know that to find the gradient(an dthen the equation) I must differentiate y and then substitute x=0.5 into the equation.
How do I expand (3x + ln2x)^2 into a form suitable for differentiation?
Regular poster

Post Number: 42
Posted on Tuesday, 10 January, 2012 - 04:36 pm:   

You shouldn't need to expand it - have you heard of the chain rule?

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