Explanation for Question 9 From the Math (No Calc) Section on the Official Sat Practice Test 6
Question nine asks us if route X plus route nine equals route 64. 2 What is the value of X? All right, 3 so let's write this out a little bigger to the side. We've got squared 4 of X plus square root of nine equals square root of 5 64. Okay. 6 So one thing to notice here is that both of these square roots, 7 the squared of nine and the squared of 64 can be done. 8 We don't have to leave them in the square root form. So the square 9 root of nine is three, because three squared equals nine. 10 So therefore the square root of nine is equal to three. 11 And then the square root of 64 is going to be equal to eight, 12 just because eight squared equals 64. 13 So the skirt of 64 is equal to eight. 14 So when you've got the square root of X, plus three is equal to 15 eight. So subtracting three, 16 from both sides, we get X is equal to, 17 or the squared of X, excuse me, is equal to five. 18 Now to cancel out this square root, 19 we can square both sides. So now we get axes equal to five squared, 20 which is equal to 25 and we can circle C as our in.