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Maths
A Level

A curve is defined by the parametric equations x=t^2/2 +1 and y=4/t -1. Find the gradient of the curve at t=2 and an equation for the curve in terms of just x and y.

To find the gradient of the curve at t=2 we need to find an expression for dy/dx and then substitute in for t=2. We can make use of the chain rule to find this expression because dy/dx = (dy/dt)/(dx/dt) a...

Answered by Steven C. Maths tutor
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Integrate x*ln(x) with respect to x

First identify that integration by parts is required. Then seperate the integration so u = ln(x)     dv/dx = x then, du/dx = 1/x  v = (1/2)x^2 . And using the integration by parts formula with these subst...

Answered by Ana S. Maths tutor
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Derive the following with respect to x1: y=(x1*x2)/(x1+x2).

y is a function of x1 and x2. We are asked to derive y with respect to x1, meaning that x2 remains constant. 

Note that y' is the deriva...

Answered by Thaleia K. Maths tutor
7324 Views

By using the substitution x = tan(u), find the integral of [1 / (x^2+1) dx] between the limits 1 and 0

First we need to change the limits, and by plugging in 1 and 0 to our substitution we find that the limits for u are arctan(1) and arctan(0) (or pi/4 and 0). Then we need to substitute for dx, and by diff...

Answered by Ollie W. Maths tutor
10670 Views

The mass of a substance is increasing exponentially. Initially its mass is 37.5g, 5 months later its mass is 52g. What is its mass 9 months after the initial value to 2 d.p?

M=37.5ekt 52=37.5ek5 52/37.5=e5k ln(52/37.5)=5k (1/5)(ln(52/37.5))=k k≈0.06538 when t=9, M=37.5e9*0.06538 M=67.54

Answered by Riccardo R. Maths tutor
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