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In a group of 120 people, 85 have black hair, 78 have brown eyes and 20 have neither black hair nor brown eyes. Find the probability of a random person being picked having black hair, given they have brown eyes

We are told that the person already has brown eyes, and this includes 78 people.We are asked to find the probability of them also having black hair.This means the person has to have brown eyes and black h...

Answered by Daniel C. • Maths tutor

2823 Views

Using the trigonometric identity for tan(A + B), prove that tan(3x)=(3tan(x)-tan^3(x))/(1-3tan^2(x))

tan(3x)=tan(2x+x), by using the identity for tan(A+B)=(tan(A)+tan(B))/(1-tan(A)tan(B)),tan(3x)=tan(2x+x)=(tan(2x)+tan(x))/(1-tan(2x)tan(x)), using it again for tan(2x),tan(3x)=tan(2x+x)=([(tan(x)+tan(x))/...

Answered by Ivan R. • Maths tutor

9617 Views

Solve the following simultaneous equations: x^2 + 2y = 9, y = x + 3

When solving simultaneous equations, there are two methods: substitution and elimination. For this question, as one of the equations is a quadratic, the substitution method has to be used. The second equa...

Answered by Chloe L. • Maths tutor

2931 Views

Factorise 6x^2 - 12x

common factor is 6x therefore it is 6x(x-2)

Answered by Huy H. • Maths tutor

5919 Views

a curve is defined by y=2x^2 - 10x +7. point (3, -5) lies on this curve. find the equation of the normal to this curve

equation of tangent is y - y1 = m(x-x1). differentiating y gives us the value of m. so dy/dx = 4x-10. we know x is 3. therefore, dy/dx = m = 2 but we need equation of the normal, which is y-y1=(1/m)(x-x1)...

Answered by Huy H. • Maths tutor

3279 Views