Solve the equation x^2 + 8x = -15
We first notice it's a quadratic equation in x so we want to make one side of the equation equal to 0.By adding 15 to both sides we get : x2 + 8x + 15 = 0We then look for two numbers which multiply to 15 and add to make 8 to help us factorise the LHS . The numbers are 3 and 5 so the equation becomes: (x+3)(x+5) = 0Therefore either x + 3 = 0 so x1 = -3or x + 5 = 0 so x2 = -5
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