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y = 4sin(x)cos(3x) . Evaluate dy/dx at the point x = pi.

By product rule:u = 4sin(x) v = cos(3x)du/dx = 4cos(x) dv/dx = -3sin(3x)dy/dx = u (dv/dx) + v (du/dx)dy/dx = 4sin(x) * -3sin(3x) + cos(3x) * 4cos(x)dy/dx = -12sin(x)sin(3x) + 4cos(x)cos(3x)Evaluate at x = pi...
WF
Answered by Will F. • Maths tutor
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What is a logarithm?

We can explain this by taking a simple power equation such as 2 3 = 8 and setting each number as an unknown variable. For instance 2 3 = x is solved by cubing 2, x 3 = 8 is solved by taking the cube root of ...
DW
Answered by Daniel W. • Maths tutor
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Use integration to find the exact value of [integral of] (9-cos^2(4x)) dx

you cannot integrate cos^2(4x) without making substitutions first. Use the cos^2(x) + sin^2(x) = 1 identity with the cos(2x)=cos^2(x)-sin^2(x), rearrange to get the identity cos(2x) = 2cos^2(x) - 1, then cos...
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Answered by Anna F. • Maths tutor
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Solve the equation sec^2(A) = 3 - tan(A), for 0<= A <= 360 (degrees)

Using simple trig identities, we know tan^2(A) + 1 = sec^2(A).Substituting for sec^2(A) into our equation, we get: tan^2(A) + 1 = 3 - tan(A).Moving this over to one side, we get the quadratic in terms of tan...
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Answered by Lachlan F. • Maths tutor
4142 Views

How should I prepare to write a commentary on an unseen poem?

Although the unseen poetry section of an exam can seem intimidating, in my experience I've found it useful to begin by annotating the poem, and then using these annotations to structure your commentary. Ther...
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