Test 10 section 4 number 28

In this question, you’re given the equation of a parabola in factored form: . Setting aside the unknown constant , there’s a lot we know from looking at the equation.

First, we know the parabola opens upwards, because when that binomial is FOILed out, the term will be positive.

Second, we know that the function has a zero (which means the parabola has an -intercept at .

The question asks us to pick a graph that could could represent the parabola, so let’s look at our choices.

• Choices A and B open downwards, so they’re out.
• Choice C opens upwards, but it doesn’t have an -intercept at , so it’s out, too.
• Choice D is correct. It opens upwards and it has an -intercept at .