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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=xr and y=12r. Hence, r= 12/x =y/12 => xy=144 => k=144 (cros...

Answered by Stamatis S. • Maths tutor

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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...

Answered by Nicky M. • Maths tutor

3901 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 t...

Answered by Zachary M. • Maths tutor

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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 met...

Answered by Scott W. • Maths tutor

7589 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:x²+3x-18=0This is a factorisation problem. To find the solutions, factorise:-Factors of x² are 1 and 1, so answe...

Answered by George H. • Maths tutor

3227 Views