Solve the simultaneous equations: 3x + y = -9, x^2 + 2x - 3 = y
Rearrange the first equation to equal 'y' so y = -9 - 3xSubstitute this into equation 2 so x^2 + 2x - 3 = -9 - 3xRearrange this to equal 0 so x^2 + 5x + 6 = 0Factorise this by utilising brackets so that the numbers inside the brackets add to make 5 (the coefficient of x) and multiply to make 6 so (x+3)(x+2) = 0For this to be true, each of the brackets must equal 0 so x = -3 or x = -2Substitute these into the first equation to get y=0 and y=-3 respectively
MJ
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