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Solve algebraically the simultaneous equations x^2 +y^2 = 25, y – 3x = 13

Rearrange y - 3x = 13y = 3x + 13 2. Substitute into x^2 +y^2 = 25x^2 + (3x + 13)^2 = 25 3. Expand bracketx^2 +(9x^2 + 39x +39x +169) = 25 4. Form quadratic equation 10x^2 + 78x + 144 = 0 (Dividing by 2 makes...
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Answered by Emily N. • Maths tutor
5226 Views

There are 5 girls, 6 boys and some adults in a classroom. The probability that a girl is chosen is 1/3. What is the probability of an adult being chosen?

This is a question taken straight out of an Edexcel exam paper. I think it's a good test of GCSE level probability and algebra. We don't know how many adults there are to begin with so let's say n = number o...
JM
Answered by Jack M. • Maths tutor
10337 Views

John is n years old where n is an whole number. Kim is three years younger than John and Vanessa is half of Kim's age. Write an expression for Vanessa's age in terms of n.

Just to make things easier to write I will be using some letters to mean things.I will write:J = John's ageK = Kim's ageV = Vanessa's age.So John is n years old so John's age is n --> J = n. Kim is three ...
JM
Answered by Jack M. • Maths tutor
5325 Views

Express the recurring decimal 0.21313... as a fraction.

x = 0.21313... 10x = 2.1313...1000x = 213.1313...1000x - 10x = 211990x = 211x = 211/990
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Answered by Miranda Z. • Maths tutor
6891 Views

Expand and simplify (2x+4)(x+2)

In order to expand this expression, we use what is known as the FOIL method. This stands for First, Outside, Inside and Last. First, we multiply the first term in each bracket by each other. 2x multiplied by...
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Answered by Erin D. • Maths tutor
10466 Views