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"A chromium compound contains 28.4% sodium and 32.1% chromium by mass, while the rest is oxygen. What is the empirical formula of this compound?"

Start with the definition of empirical formula so we know what we are trying to work out. Empirical formula is the simplest whole-number ratio of elements in a compound. First, let us work out how much of th...
MP
Answered by Mia P. • Chemistry tutor
5759 Views

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
3696 Views

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...
AF
Answered by Anna F. • Maths tutor
7951 Views

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
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