+186 A parabola with equation y=ax^2+bx+c has a vertical line of symmetry at x=2 and goes through the two points (1, 1) and (4, -7). The quadratic ax^2+bx+c has two real roots. The greater root is sqrt(n)+2. What is n?
+118673 A parabola with equation y=ax^2+bx+c has a vertical line of symmetry at x=2 and goes through the two points (1, 1) and (4, -7). The quadratic ax^2+bx+c has two real roots. The greater root is sqrt(n)+2. What is n?
The axis of symetry is just -b/2a
so -b/2a = 2
-b = 4a
b=-2a
So the equation so far becomes y=ax^2 -2ax +c
Sub in your two points and solve simulataneously and what do you get for a and c
Can you take it from here?
+186 I'm facing another problem now - I got the quadratic equation -8/9x^2+16/9x+1/9=y, but the axis of symmetry is x=1, not x=2.
