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Answer is 60.

[ 2x - 3y = 7 ] *3 = [ 6x - 9y = 21 ]

[ 3x + 4y = 2 ] *2 = [ 6x + 8y = 4 ]

[ 6x + 8y = 4 ] - [ 6x - 9y = 21 ] = [ 17y = -17 ] 

Therefore, y = -1.

Substituting y = -1 into the o...

The factors of a number are all the numbers that divide into it, so the HCF of two numbers is the highest number that is a factor of both numbers. I'd work it out by create a list of all of the prime fact...

x²-9x-10=0

1. Find two numbers that add to equal -9 and mulitiply to equal -10
   
2. These numbers are -10 and 1 so this equation factorises to equal (x-10)(x+1)=0
   
...

(a) Gradient (m) = (y₂-y₁)/(x₂-x₁) = (10-4)/(1-(-2)) = 6/3 = 2

(b) General equation of a straight line: y = mx + c    (c = y-intercept)

For our st...