Top answers

Using the binomial theorem, find the coefficient of x^4*y^5 in (x-2y)^9.

The term containing x 4 y 5 will be C(9, 5) x 4 (-2y) 5 = (9!/(5!4!)) x 4 (-2) 5 y 5 The coefficient of which will be 126 -32= -4032
GH
Answered by George H. • Maths tutor
4020 Views

There are 48 girls in a large cheerleading squad. The ratio of girls to boys in this squad is 8:3. How many boys are in the squad?

There are (48/8)*3=18 boys. Since the ratio of boys to girls is 8:3 you divide the number of girls by 8 which gives 6 and then multiply by 3 to give the number of boys.
GH
Answered by George H. • Maths tutor
3277 Views

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 hair...
DC
Answered by Daniel C. • Maths tutor
3327 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))/(1-...
IR
Answered by Ivan R. • Maths tutor
11407 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 equatio...
CL
Answered by Chloe L. • Maths tutor
3483 Views