Top answers

A sequence of numbers have the property that x, 12, y, where x > 0, y > 0, form a geometric sequence while 12, x, 3y form an arithmetic sequence. A)If xy = k, find k. B)Find the value of x and y.

A) Since x, 12, y form a geometric sequence, we know that there exists some real number "r" (common ratio) such that 12=x r and y=12 r. Hence, r= 12/x =y/12 => xy=144 => k=144 (cross multiply...
SS
Answered by Stamatis S. • Maths tutor
1811 Views

If the probability of picking a red ball out of bag A is 2/5 and the probability of picking a red ball out of bag B is 3/7, what is the chance that you will pick exactly 2 red balls if you pick 2 balls from A and 1 ball from B? The balls are not replaced.

Draw a tree diagram. Recognise that the second ball selected from bag A is dependent on the outcome of the first ball. The outcome of the ball selected from B is independent. There are 3 orders that 2 red ba...
NM
Answered by Nicky M. • Maths tutor
4850 Views

How do you factorise x^2 - 4?

x^2 - 4 consider that in any quadratic the two numbers which end up in the brackets at the end must add up to the middle term in x. they must also multiply to make the number at the end of the quadratic term...
ZM
Answered by Zachary M. • Maths tutor
10220 Views

Show that (x+1)(x+2)(x+3) can be written in the form ax^3 +bx^2 + cx + d where a,b,c,d are positive integers.

First we shall expand two of the brackets to obtain a quadratic equation and then multiply each term by the remaining bracket. The order with which we expand the brackets does not matter. Use the FOIL method...
SW
Answered by Scott W. • Maths tutor
10037 Views

Tom thinks of a number. He squares it, adds 3 times the original number and then subtracts 18. The result is 0. What two numbers could Tom have been thinking of?

Formulate the problem algebraically:x 2 +3x-18=0This is a factorisation problem. To find the solutions, factorise:-Factors of x 2 are 1 and 1 , so answer will take the form: (x +- ?)(x +- ?)=0-List pairs of ...
GH
Answered by George H. • Maths tutor
4080 Views