here is a sketch of y=x^2 + bx + c. the curve intersects the x-axis at (2,0) and point P. the y-axis at (0,14) work out the x-coordinate of the turning point of the graph

Question
Answer:
To find the turning point, or vertex, of this parabola, we need to work out the values of the coefficients b and c.

We are given two different solutions of the equation.

First, (2, 0). 
[tex]0=(2)^2+2b+c\\-4=2b+c[/tex]

Second, (0, 14).
[tex]14=(0)^2+0b+c\\c=14[/tex]

So we have a value (14) for c. We can substitute that into our first equation to find b.

[tex]-4=2b+c\\-4=2b+14\\-18=2b\\b=-9[/tex]

We can now plug in our values for b and c into the equation to get its standard form.

[tex]y=x^2-9x+14[/tex]

To find the vertex, we can convert this equation to vertex form [tex]y=a(x-h)^2+k[/tex] by completing the square.

[tex]y=x^2-9x+14[/tex]

[tex]y=x^2-9x+(-4.5)^2+14-(-4.5)^2[/tex]

[tex]y=x^2-9x+20.25+14-20.25[/tex]

[tex]y=(x-4.5)^2-6.25[/tex]

Thus, the vertex is (4.5, –6.25).

We can confirm the solution graphically (see attachment).
solved
general 10 months ago 5297