Question

y=2x^2-7x+7
the function above crosses the x-axis once.
True or false?

Answer 1

false

Answer 2

y=2x^2-7x+7
2x^2-7x+7=0

Answer 3

Thank you:)

Answer 4

as I showed before it doesn't cross the x axis at all..

Answer 5

solve that equation

Answer 6

Isn't this the same question?

Answer 7

http://www.wolframalpha.com/input/?i=Graph%28y%3D2x%5E2-7x%2B7%29
it is..

Answer 8

\[x=\frac{7 \pm \sqrt{49-4(2)(7)}}{4}\]
since this is imaginary
there are no x-intercepts
the graph does not touch x-axis

Answer 9

Yes, but how can we see that mathematically?
A function crosses the x axis, when y=0.
So, let's set the equation equal to 0 and solve for x. That will tell us what places the graph crosses.

So we get 2x^2-7x+7 = 0
Using the quadratic formula, we get x = (7 +/- sqrt(49 - 56)) /4 = (7 +/- sqrt(-7))/4

So since the sqrt is of a negative number, there is no real solution.