Video Transcript
Which of the following graphs
represents the equation 𝑦 equals 𝑥 squared minus five 𝑥 plus eight?
We can make a table to come up with
a few points to plug on these graphs. What is 𝑦 when 𝑥 equals zero? 𝑦 would equal zero squared minus
five times zero plus eight. When 𝑥 is zero, 𝑦 equals
eight. If we plug that point on all of the
graphs, we see that the lines on graphs d and e do not go through the point zero,
eight. Graphs d and e can’t represent this
equation.
Let’s choose another value for 𝑥
to find a second point on our graph. Let’s consider when 𝑥 equals
one. When 𝑥 equals one, 𝑦 equals one
squared minus five times one plus eight. One minus five equals negative
four. Negative four plus eight equals
four. This graph should have a point at
one, four.
Okay, let’s consider the point one,
four. a goes through one, four. b does not go one- through one, four. And c does not go through one,
four. b and c cannot graph this equation. Using a table, we’ve narrowed down
the graph to a.
