The discriminantEdexcel International A Level Maths: Mind map

Exam questions on The discriminant

1. Consider the equation $x^2-4x+7=0$.
   Explain what the value of the discriminant tells you about the graph of $y=x^2-4x+7$.2 marks
2. The equation $x^2+kx+9=0$, where $k$ is a positive constant, has equal roots.
   Solve $x^2+kx+9=0$ for this value of $k$.2 marks
3. The line $y=2x+c$ and the curve $y=x^2-3x+4$, where $c$ is a constant.
   Show that the $x$-coordinates of any points where the line meets the curve satisfy $x^2-5x+(4-c)=0$, and show that the discriminant of this equation is $4c+9$.3 marks