Explanation for Question 15 From the Math (No Calc) Section on the Official Sat Practice Test 6
Question 15 asks, which of the following is equivalent to a plus B 2 over two squared. The first thing to remember here is that you 3 can not distribute the exponent. 4 So this expression right here is not equivalent to a squared 5 plus B over two squared. And that's a really easy mistake to make, 6 but do not do this because it's a very kind of quick way to 7 unfortunately lose some points. So what you're really going to want to do 8 is distribute that squared or not distribute. 9 You're going to essentially, um, convert this into a simple expression. 10 So make it a plus B over two times a plus B over two, 11 since that's the definition of squared, it's this expression times itself. 12 And now from here, it's just simply foiling it out and seeing what we're 13 left with. So we've got a times a, 14 is a squared. We've got a times B over two, 15 which has plus a B over two. 16 And then we've got B over two times a, 17 which is again a B over two. 18 And then we've got B over two times B over two. 19 So that's going to be B squared over four. 20 And now just to write that out, the reason for that is because when 21 you multiply two fractions, you're going to multiply the top, 22 which gets you to B squared. And then you're going to multiply the bottom, 23 which gets you to four. So, 24 okay. We've got a squared plus a B over two plus a B over 25 two is just going to be AB since it's essentially one half AB plus 26 one half AB it's like it's two, 27 one AB. So just AB plus B squared over 28 four. And that's it. 29 We can pick D as our answer choice for question 15.