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Solve to find sin x , 4cos^2 + 7sin x -7 =0

4cos 2 x + 7 sinx - 7 =0 we know that sin 2 + cos 2 = 1 so 4(1-sin 2 x) + 7sinx -7 = 0 if we times out the brackets -4sin 2 x + 7 sinx -3 =0 4sin 2 x -7sinx +3 =0 (4sinx-1)(sinx +2)=0 so therefore sinx =1/4 ...
JP
Answered by Jo P. • Maths tutor
4065 Views

Find a and b (both real) when (a+b*i)^2=i.

Every complex number has a real and imaginary part. For the complex number z=a+bi the notation for real and imaginary parts respectively are Re(z)=a and Im(z)=b . If you know this, many complex algebra equat...
UA
Answered by Urte A. • Maths tutor
1947 Views

Expand and simplify (x+4)(x-3)

We need to multiply out each bracket and it is best to do this systematically, multiplying each term in the left hand bracket by each term in the right hand bracket. (x+4)(x-3) = (X x X) + (X x -3) + (4 x X)...
EM
Answered by Eleanor M. • Maths tutor
33721 Views

There are 300 passengers on a plane, 7/20 of them are men, 30% are women, the rest are children. Work out the number of children.

300 x (7/20) = 300/20 x 7 = 15 x 7 = 105 = number of men on the plane. 300 x 0.3 = 90 (Or 300/10 x 3) = number of women on the plane. 105 + 90 = number of adults on the plane = 195. 300 - 195 = 105 = number ...
HT
Answered by Hannah T. • Maths tutor
5630 Views

Put the next fractions in an increasingly order: 1/2, 3/4, 2/3, 5/6

To solve the problem, we will have to find the maximum common denominator (mcd). We decompose the denominator of every fraction obtaining, 2=2; 3=3; 4=2 2 ; 6=2x3. Now, we take the common factors with the bi...
LA
Answered by Lucia A. • Maths tutor
8164 Views