Question

In f(x) = 2x2 − 8x − 10, the y-intercept is ? at ? and the x-intercepts are (-1, 0) and ? .

Answer 1

1.  y-intercept

$\boxed{(0,-10)}$

The quadratic function $f(x)=2x^22-8x-10$ represents a parabola. In fact, the graph of a quadratic function is a special type of U-shaped curve called a parabola. To find the y intercept, we set $x=0$ as follows:

$f(x)=2x^2-8x-10 \\ \\ If \ x=0 \rightarrow f(0)=-10 \\ \\ Then \ y-intercept: \\ \\ (0,-10)$

2.  x-intercepts

$\boxed{(-1,0) \ and \ (5,0)}$

To find the other x-intercept, we must set $y=0$ as follows:

$f(x)=2x^2-8x-10 \\ \\ If \ y=0 \rightarrow 2x^2-8x-10=0 \\ \\ Using \ the \ quadratic \ formula: \\ \\ x=\frac{-b \pm \sqrt{b^2-4ac}}{2a} \\ \\ \therefore x=\frac{-(-8) \pm \sqrt{(-b)^2-4(2)(-10)}}{2(2)} \\ \\ \therefore x_{1}=-1 \ and \ x_{2}=5$

Therefore, the other x-intercept is $(5,0)$. You can see both the y-intercept and the x-intercepts in the figure below.