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Given that cos(x) = 1/4, what is cos(2x)?

cos(2x) = 2cos 2 (x) - 1 This is the identity. Therefore we can substitute in 2[cos 2 (x)] to be 2 multiplied by (1/4) 2 .Therefore cos(2x) = 2(1/4)(1/4) - 1 = 2/16 - 1 = 2/16 - 16/16 =1/8 - 8/8 = -(7/8).Ans...
BK
Answered by Bhumi K. • Maths tutor
9962 Views

Expand (2x+4)(x-3)

2x^2 - 2x - 12
AS
Answered by Amy S. • Maths tutor
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n is an integer such that 3n + 2 < 14 and 6n/(n^2+5) > 1. Find all possible values of n.

First of all, solving the equation 3n + 2 &lt; 14 to find n. 3n &lt; 14 -2 = 3n &lt; 12. n &lt; 12/3 = n &lt; 4Secondly solve the equation 6n/(n^2+5) &gt; 1 to find n. Collect all terms on one side of the to...
KP
Answered by Kai P. • Maths tutor
21405 Views

Split (3x-4)/(x+2)(x-3) into partial fractions

(3x-4)/(x+2)(x-3) = A/(x+2) + B/(x-3)=&gt; 3x-4 = A(x-3) + B(x+2)Let x = -2-10 = -5AA = 2Let x = 35 = 5BB = 1∴ (3x-4)/(x+2)(x-3) = 2/(x+2) + 1/(x-3)
Answered by • Maths tutor
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Solve the quadratic equation (x^2)-x-12=0 (easy), (x^2)-9=0 (special case), (x^2)+5x-13=0 (quadratic formula)

For each of the above the methodology is fairly similar, first try and do it just by looking at it then try the quadratic formula if that doesn't work. At GCSE level I don't think there's any need to worry a...
JE
Answered by Jack E. • Maths tutor
3561 Views