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How do I rationalise the denominator? (Surds)

If you have a fraction where the denominator is a surd, such as 5/(1+sqrt(2)), you need to multiply the denominator by another number so that it becomes a a whole number. If you multiply either the denominat...
LC
Answered by Leanne C. • Maths tutor
3706 Views

factorise: 3x^2+13x-30

(3x-5)(x+6)factors of 90 (3x30): 1x90, 6x15, 9x10, 5x18and add up to 13 can only be 5 and 1818-5=13 5/3 or 18/3=6 and 5x6=30so must be (3x-5)(x+6) and check by expanding with FOIL method
MS
Answered by Mary S. • Maths tutor
3913 Views

Why is it that the sum of all natural numbers up to n is 1/2(n)(n+1)?

First let's consider the case of even numbers. Suppose n is even, then it must be double some other number, so we have: n = 2k Where k is another natural number. We want to find out what: 1 + 2 + ... + (n - ...
IM
Answered by Ibrahim M. • Maths tutor
4581 Views

Bob buys a car for £120 after it is reduced by 20% in the sale. What was the original price of the car?

£120 is the price of the car after it has been reduced by 20%. This means that £120 is equal to 80% of the original price.2 ways to work this out:1) £120 = 80 % £ ? =100%therefore: £? = (120 x 100)/8012000/8...
MP
Answered by Mary P. • Maths tutor
5600 Views

How can I solve reverse percentage questions?

A bag in a sale is reduced by 20%. It now costs £40. What was the original price? Solution 1: Using ratios and basic percentagesA good way to solve this problem is by thinking about what percentage is left a...
MB
Answered by Madeleine B. • Maths tutor
4717 Views