Who can solve quadratic and simultaneous quations ?
The parabola y = (2x+3)^2 crosses the horizontal line y = 4, in two places which are when (2x+3)^2 = 4 so this is the interpretation of this equation on a graph. We will get the two results that we expect, because 4 has two square roots, +2 and -2 Taking the square roots of both sides. Either 2x+3 = 2 or 2x+3 = -2 x = -1/2 or x = -5/2 2) Once again we may interpret this as the line x – 2y = 7 crossing the parabola x^2 +4y^2 = 37 which will be in two places. As we expect two results we substitute from the line equation into the parabola equation, (using either x or y) Substituting x = 2y + 7 yields (2y + 7)^2 + 4y^2 – 37 = 0 8y^2 + 28y +12 = 0 dividing this by four, 2y^2 + 7y +3 = 0 [if you do not see how to factor at this stage use the quadratic formula].