Explanation for Question 15 From the Math (No Calc) Section on the 2019 April Sat
And number 15, we are given an equation and we are trying to find 2 the graph of that equation. So the very first thing I would look for 3 is the direction of the parabola. Since this is a positive X squared out 4 front, you know, that it's going to be facing upwards and all of the 5 problems are facing upwards. So we're good. 6 Then we can start looking at the Y intercept, 7 which is this coefficient being added at the end of standard form of an 8 equation. So the y-intercept is two and all of the graphs 9 cross off at two. So we can't eliminate any choices with that either. 10 So next I would think about the X intercepts and 11 defined X intercepts. It's easiest to factor, 12 but since we are looking for a number that multiplies to two and adds 13 to two that does not give us any help at all. 14 So we're going to have to use quadratic formula. 15 If you don't have it memorized, you definitely should memorize it, 16 but it is negative B plus or minus the square root of B squared 17 minus four, AC all over to a, 18 we know R a is equal to one. 19 B is equal to two and C is equal to two just by looking 20 at those numbers there. So now plugging that in, 21 you get negative two plus or minus the square root of two 22 squared, minus four times one times 23 two, all over two times one. 24 So simplifying that you get negative two plus or minus, 25 we get four minus eight all over 26 too. So I'm not actually going to go through and solve this out since 27 it's a waste of time and y...