SAT Question of the Day (plus ACT!): Apr. 19, 2014

If you are reading this in an email you received from me, do not click the link to sat.collegeboard.org below. Use the link to my website that is farther down on the email.

http://sat.collegeboard.org/practice/sat-question-of-the-day?questionId=20140419&oq=1 (This link takes you to today’s question. If you use my archive, you will see the question related to my SAT explanation for that date.)

The answer is A.  If the line y=a intersects a quadratic function in only one place, it has to be at the minimum or lowest point of a parabola.  (If a, see below, is negative, the parabola is upside down and the highest point is called a “maximum” but my strategy still works.

You can find the minimum the way the SAT folks explain it.  That will take you quite a bit of extra time.  Let’s do it a Wizardly way!

The easy way is to memorize and use this formula for finding the minimum: c – (b2/4a).  For the function in the question, f(x)=x2-6x+8, where a=1, b=6, and c=8, that would be: 8 – (62/4) = -1.  All done!

How easy was that?  Not bad.  Be sure to memorize this formula and if you see a similar question on the SAT or ACT you’ll get a quick point that most other students will miss.  (Only 32% are getting this question correct!)  That will be a big advantage on test day.

Let’s see what the ACT folks have for us today.

The answer is C.  Just like Ms. Murphy was helpful yesterday, she strikes again!  Shorter is better.  Answer C, “one final,” says the same thing as all the other answers but using fewer words.  That works.

QotD Words of “Wiz-dom”:

Here’s an “atta boy!” from the Wizard for working on your SAT and/ACT score on a Saturday.  This practice is going to pay off.  Nice work.