In the quadratic equation above, is a constant. The graph of the equation in the contains the points and . What is the value of ?
We know the function passes through the points (-2, 0) and (6, 0). We also know that the function value, or the y value, is equal to the value of the X squared minus 4 times the value of X plus C.
We can use either point to find the value of C.
We will prefer to use a positive X value (easier to calculate with positives).
6 squared is 36 minus 4 times 6 (24) is 12. 12+C equals the Y value – which is zero when X=6. In this case it is clear C must equal -12.
The same can be done with the other point (-2, 0).
50% out of >140,000 answers – a moderate level of difficulty. If you had problems with understanding the solution – you should review function, quadratics, graphs, and solving equations with one variable.