<p>Hello! I scored a 670 on SAT math, but a 770 on SAT II math and I a five on AP calc…just wondering what this means and what I can do to improve my math score?</p>
<p>This is slightly the same to the my situation. All the math classes I’ve had, I had a final grade of 97+ but I took the Barron’s SAT Diagnosis test and received 500-540…</p>
<p>I have had continuous 730-800 on SAT I math. You just have to learn the certain approaches on how to solve the problem. One important tip: YOU MUST READ THE ENTIRE QUESTION CAREFULLY. You might miss out on some very important information. Here, I’ll show you an example of a very difficult SAT math problem:</p>
<p>If 0≤ x ≤ y and (x + y)^2 − (x – y)^2 ≥ 25, what is the least possible value of y?</p>
<p>If you look at this problem, there is no way you can solve it using regular school math methods. You have to take some time and think about the problem. (Don’t worry…I was in your situation once…)</p>
<p>They’re asking for the least possible value of y, right? Well, you have your first hint: y is at its least possible value when y = x (Take note of the inequality sign…say that x = 1…what’s the least possible value of y? Answer: 1, because of the inequality sign) Take note: if you haven’t noticed the inequality sign, you might have gotten the wrong answer.</p>
<p>Next, plug in the x’s in the equation for y’s (you’re making a substitution)</p>
<p>(y + y)^2 − (y – y)^2 ≥ 25</p>
<p>Now, simplify using algebra…</p>
<p>(2y)^2 - 0 ≥ 25
4y^2 ≥ 25
Then, take the square root of both sides.
2y ≥ 5
y ≥ 5/2
(5/2 is actually the correct answer)</p>
<p>As you can see in the example problem, SAT math problems aren’t regular high school math problems. They are problems that are testing the knowledge that you learned in high school. They want to see if you can apply that knowledge to their math problems.
Hopes this helps! By curiosity, what’s your guys’ CR scores on your practice tests?</p>
<p>I’m not so sure if I would jump ahead and claim y=x, mostly because x is not fixed (can you prove your result?). It works in this case, but not on most harder inequality problems.</p>
<p>You can use difference of squares to get 4xy >= 25, xy >= 25/4. You can rigorously prove that y >= 5/2 by contradiction, and min(y) = 5/2 when x=y.</p>
<p>MITer94,
I plugged in my answer (5/2) to both x and y, and the answer comes out as 25 ≥ 25. That _ under the inequality means that x is “less than OR EQUAL TO y”</p>
<p>And differences of squares would take a long time to solve this problem…I rather try to solve it quickly, carefully, and efficiently.</p>
<p>I know that, I’ve scored 800 on math consistently.</p>
<p>Here’s a problem: Let 0 <= x <= y, and xy = 4. Find the least possible value of x+2y.</p>
<p>ok…what do the <= stand for?</p>
<p>Less than or equal…I’m typing on my phone. Too much of a hassle to type the correct symbol.</p>
<p>What MITer is getting at, is the way you attacked the problem above would not always work.</p>
<p>Also, OP</p>
<p>A score in the high 700s on the subject test can mean 5 or more wrong answers.</p>
<p>A 670 on the SAT Math, can mean the same/similar number.</p>