Explanation for Question 10 From the Math (No Calc) Section on the 2018 March Sat
Question 10 says in the function above K is a constant. 2 If two is a zero of the function, 3 what is the value of K? So if two is a zero of 4 the function, that means that X minus two is one of the factors 5 of this function. So X squared, 6 minus 11, X plus K factors into X minus two, 7 and then X minus something else or X plus something else. 8 We're just going to call that Y for right now, 9 now, because this is just how factoring works. 10 We know that negative two plus Y 11 is equal to negative 11 and that negative two times 12 Y is equal to K. So let's start by just setting negative two 13 plus Y equal to negative 11. 14 And that tells us that Y is equal to negative nine. 15 Now we can plug that into negative two times Y and do negative two 16 times negative nine, and that gives us 18. 17 And so we know that the value of K must be positive 18 18 or answer choice.