Explanation for Question 20 From the Math (Calc) Section on the 2019 April Sat
Well, we're number 20. We want to know if X is a solution that 2 the equation above, what is the value of the square root of X minus 3 three? I think the easiest way to do this one would be to solve 4 for X and then use that to plug it into this expression here. 5 So we can start off by squaring both sides. 6 So now we have the squared of X minus three squared is just X 7 minus three. And then on the other side, 8 we have to foil. So three minus root X, 9 times three minus for decks, we have three times three is nine, 10 three times. Negative root X is negative three root X. 11 Then we have another negative three Redex and negative 12 root X times. Negative Redux is positive X. 13 So now we have two Xs on both sides. 14 We can subtract it to get rid of it. 15 So that gets rid of that. Now we have negative three equals nine. 16 We have two negative root three axes, 17 so we can combine them two negative six Redex. 18 Now we can subtract nine from both sides that 19 gives us negative 12 equals negative six Rolodex. 20 We can multiply by negative one to get rid of the negative. 21 So 12 equals six vertex, 22 then divide by six on both sides. 23 We get two equals and vertex and then scoring, 24 but size you get that X is equal to four. 25 So now we can plug that in to this expression here. 26 So the square root of four minus three is equal to the 27 square root of one, which is just one. 28 So the answer is.