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Given that α= 1+3i is a root of the equation z^3 - pz^2 + 18z - q = 0 where p and q are real, find the other roots, then p and q.

All coefficients of z are real, therefore one root must be the complex conjugate so β = 1-3i.It is known that Σαβ = 18 (the coefficient of z), so we can get an equation in the third root, γ, as follows: Σαβ ...
ZG
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find an expression for the sum of the series of 1 + 1/2cosx + 1/4cos2x +1/8cos3x + ......

Firstly we can use the fact that cosx is the real part of e^ix. This means that the series above is the real part of the infinite series 1 + 1/2e^ix + 1/4e^2ix + ...... This means that we have an infinite ge...
NK
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Determine if these two vectors are perpendicular. a=[1,4,8], b=[0,6,-3]

Start by determining dot product. a.b = 1x0 + 4x6 + 8*-3 = 0as a.b = |a||b|cos(theta)cos(theta) = 0therefore theta = 90 degTherefore vectors are perpendicular
PD
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Differentiate arctan(x) with respect to x

We can set arctan(x) = y. Remember that arctan(x) is the inverse of tan(x), so we can take the tangent of both sides to give: tan(arctan(x)) = x = tan(y). Tan(x) has the standard derivative of sec^2(x) (whic...
SE
6057 Views

Explain why the equation tanx + cotx = 1 does not have real solutions.

First of all, we need to express tangent and cotangent in terms of sine and cosine using the identities: tanx = sinx / cosx and cotx = cosx / sinx. Substituting these expressions into the initial equation we...
SV
17637 Views