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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
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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
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what factors determine enzyme activity?

several factors play a role in the rate of an enzyme catalysed reaction. substrate concentration: The amount of substrate in the solution. The higher the concentration of substrate the more frequently they w...
JL
Answered by Jack L. Biology tutor
3917 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
4734 Views

Expand (2x-1)(x+3)

Method 1: Foil method (each term of the first bracket are multiplied by each term of the second bracket, and hence the product have 4 terms before simplifying)(2x-1)(x+3) = 2x x + 2x 3 - 1 x -1 3 =2x 2 + 6x ...
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Answered by Cherish N. Maths tutor
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