Education.com

# Tip #14 to Get a Top SAT Math Score (page 2)

By Brian Leaf
McGraw-Hill Professional

1. A   Simply plug – 2 in for x in the equation.
2. f(–2) = 2(–2)3 – 2 = –18.

3. D   The long way to solve this question is to plug (5) and (–5) into each equation in the answer choices to see which one makes f(5) < f (–5). This absolutely works and is worth the time since it will earn you points. There is also a faster way. In every other answer choice, 5 plugged in for x will clearly give the same or higher value than when –5 is plugged in. However, choice D, f(x) = 2 – x3, is the only one where a positive number yields a lower result than a negative: 2 – 53 < 2 –(–5)3 –123 < 127.
4. D   This is a very common SAT question. Just choose an (x, y) point from the table and see which equation works. Choice D is correct since 11 = 3(2)2 – 1. Try all equations, in case several work. Then you would just choose a second point to find the one answer choice that works for both points.
5. E   This is a very typical SAT question, appearing on nearly every SAT. If you got this question wrong and you spend the time to master it, you will gain points! In this question, you are given values for the number of cars, which is x, and for pints of soap, which is g(x). g(x) = 140 and x = 3. Simply plug these values in for x and g(x), and use basic algebra to solve for k. If this is confusing, redo this question over and over until you can teach it to a friend. Then do that! This is a great party question. Next time you go to a party, bring this one, people love it. OK, I'm kidding.
g(x) = 5x – (4x + k)
3 = 5(140) – (4(140) + k)
3 = 700 – 560 – k
3 = 140 – k
–137 = –k
137 = k
6. D   Plug 6 into the m function, plug 3 into the h function, and subtract the results.
7. E   f(3) means "plug 3 in for x" and get y. Usually we use an equation to answer this, but in this question we use the graph shown. We simply locate x = 3 on the graph and see what the y value is at that point. y = –2. Then the question asks for f(–2), so we look on the graph once again, but this time we plug –2 in for x. The best answer is y = .

Go to: Tip #15

150 Characters allowed

### Related Questions

#### Q:

See More Questions

### Today on Education.com

#### WORKBOOKS

May Workbooks are Here!

#### ACTIVITIES

Get Outside! 10 Playful Activities