As a graph cuts the axis when the y coordinate is zero, then we substitute \(y = 0\) into the quadratic equation and use algebra to solve. We need to factorise the trinomial. When factorised this ...

To factorise this quadratic, find two numbers that have a product of +11 and a sum of -12. \(11 + 1\) will add up to +12, not -12, so the numbers must be -11 and -1 as \(-11 \times -1 = +11\).