Question

Use the graphing calculator to graph the quadratic function y = 2x2 – 6x – 8. Which values are solutions of 0 = 2x2 – 6x – 8? Check all that apply. –4 –1 0 1 4

Answer 1

Plug the values into the second equation to see if they end up equaling 0.

-4: 2(-4)^2 - 6(-4) - 8 = 0
2(16) + 24 - 8 = 0
32 + 16 = 0
Not -4

-1: 2(-1)^2 - 6(-1) - 8 = 0
2 + 6 - 8 = 0
8 - 8 = 0
0 = 0
Yes -1

0: 2(0)^2 - 6(0) - 8 = 0
0 - 0 - 8 = 0
Not 0

1: 2(1)^2 - 6(1) - 8 = 0
2 - 6 - 8 = 0
-12 = 0
Not 1

4: 2(4)^2 - 6(4) - 8 = 0
2(16) - 24 - 8 = 0
32 - 32 = 0
0 = 0
Yes 4 ———— Or use the quadratic equation ( - b +/- sqrt( b^2 - 4ac)) / 2a ———— a would be 2– b would be -6– & c is -8

Answer 2

Answer:

x= -1 and x = 4

Step-by-step explanation:

We have to graph the quadratic function $y=2x^2-6x-8$ using the graphing calculator.

The graph has been attached.

Now, we have to find the solutions of the equation $0=2x^2-6x-8$

For this, we see at which point (s) the graph intersects the x axis. The x coordinate of these points would be the solution.

From the attached graph we can see that the graph intersects the x-axis at (-1,0) and (4,0). Hence, the x-coordinate of these points would be the solution.

Thus, the solutions of the given equation are x= -1 and x = 4