All ACT Math Resources
Example Questions
Example Question #122 : Expressions
You are told that can be determined from the expression:
Determine whether the absolute value of is greater than or less than 2.
The quantities are equal
The relationship cannot be determined from the information given.
The expression is simplified as follows:
Since the value of must be slightly greater for it to be 17 when raised to the 4th power.
Example Question #123 : Expressions
Which best describes the relationship between and if ?
The relationship cannot be determined from the information given.
The relationship cannot be determined from the information given.
Use substitution to determine the relationship.
For example, we could plug in and .
So far it looks like the first expression is greater, but it's a good idea to try other values of x and y to be sure. This time, we'll try some negative values, say, and .
This time the first quantity is smaller. Therefore the relationship cannot be determined from the information given.
Example Question #6 : Simplifying Expressions
If and , then
Cannot be determined
We have three variables and only two equations, so we will not be able to solve for each independent variable. We need to think of another solution.
Notice what happens if we line up the two equations and add them together.
(x + y) + (3x – y + z) = 4x + z
and 5 + 3 = 8
Lets take this equation and multiply the whole thing by 3:
3(4x + z = 8)
Thus, 12x + 3z = 24.
Example Question #1 : How To Simplify Expressions
Simplify the following expression: x3 - 4(x2 + 3) + 15
To simplify this expression, you must combine like terms. You should first use the distributive property and multiply -4 by x2 and -4 by 3.
x3 - 4x2 -12 + 15
You can then add -12 and 15, which equals 3.
You now have x3 - 4x2 + 3 and are finished. Just a reminder that x3 and 4x2 are not like terms as the x’s have different exponents.
Example Question #21 : Simplifying Expressions
Which of the following is equivalent to ?
abc
a2/(b5c)
ab5c
b5/(ac)
ab/c
b5/(ac)
First, we can use the property of exponents that xy/xz = xy–z
Then we can use the property of exponents that states x–y = 1/xy
a–1b5c–1 = b5/ac
Example Question #2491 : Act Math
Simplify the following expression:
2x(x2 + 4ax – 3a2) – 4a2(4x + 3a)
–12a3 – 22a2x + 8ax2 + 2x3
12a3 – 16a2x + 8ax2 + 2x3
–12a3 – 14a2x + 2x3
12a3 – 22a2x + 8ax2 + 2x3
–12a3 – 14ax2 + 2x3
–12a3 – 22a2x + 8ax2 + 2x3
Begin by distributing each part:
2x(x2 + 4ax – 3a2) = 2x * x2 + 2x * 4ax – 2x * 3a2 = 2x3 + 8ax2 – 6a2x
The second:
–4a2(4x + 3a) = –16a2x – 12a3
Now, combine these:
2x3 + 8ax2 – 6a2x – 16a2x – 12a3
The only common terms are those with a2x; therefore, this reduces to
2x3 + 8ax2 – 22a2x – 12a3
This is the same as the given answer:
–12a3 – 22a2x + 8ax2 + 2x3
Example Question #1001 : Algebra
Simplify the following expression:
(xy)2 – x((4x)(y)2 – (4x)2) – 42x2
–3x2y2 – 16x3 – 16x2
3x2y2 + 16x3 – 16x2
–3xy2 – 4x3
5x2y2
–3xy2 – 4x3 – 16x2
–3x2y2 – 16x3 – 16x2
To simplify this, we will want to use the correct order of operations. The mnemonic device PEMDAS is usually very helpful.
Parenthesis (1st)
Exponents (2nd)
Multiply, Divide (3rd)
Add, Subtract (4th)
PEMDAS tells us to evaluate parentheses first, then exponents. After exponents, we evaluate multiplication and division from left to right, and then we evaluate addition and subtraction from left to right.
Let's look at (xy)2 – x((4x)(y)2 – (4x)2) – 42x2
We want to start with parentheses first. We will simplify the (xy)2 by using the general rule of exponents, which states that (ab)c = acbc. Thus we can replace (xy)2 with x2y2.
x2y2 – x((4x)(y)2 – (4x)2) – 42x2
When we have parentheses within parentheses, we want to move from the innermost parentheses to the outermost. This means we will want to simplify the expression (4x)(y)2 – (4x)2 first, which becomes 4xy2 – 16x2. We can now replace (4x)(y)2 – (4x)2 with 4xy2 – 16x2 .
x2y2 – x(4xy2 – 16x2) – 42x2
In order to remove the last set of parentheses, we will need to distribute the x to 4xy2 – 16x2 . We will also make use of the property of exponents which states that abac = ab+c.
x2y2 – x(4xy2) – x(16x2 ) – 42x2
= x2y2 – 4x2y2 – 16x3 – 42x2
We now have the parentheses out of the way. We must now move on to the exponents. Really, the only exponent we need to simplify is –42, which is equal to –16. Remember that –42 = –(42), which is not the same as (–4)2.
x2y2 – 4x2y2 – 16x3 – 16x2
Now, we want to use addition and subtraction. We need to add or subtract any like terms. The only like terms we have are x2y2 and –4x2y2. When we combine those, we get –3x2y2
–3x2y2 – 16x3 – 16x2
The answer is –3x2y2 – 16x3 – 16x2 .
Example Question #21 : How To Simplify An Expression
If both and are positive, what is the simplest form of ?
can also be expressed as
Example Question #2 : How To Simplify Expressions
Which of the following does not simplify to ?
All of these simplify to
5x – (6x – 2x) = 5x – (4x) = x
(x – 1)(x + 2) - x2 + 2 = x2 + x – 2 – x2 + 2 = x
x(4x)/(4x) = x
(3 – 3)x = 0x = 0
Example Question #1 : Simplifying Expressions
Simplify the result of the following steps, to be completed in order:
1. Add 7x to 3y
2. Multiply the sum by 4
3. Add x to the product
4. Subtract x – y from the sum
28x + 11y
28x – 13y
28x + 13y
29x + 13y
28x + 12y
28x + 13y
Step 1: 7x + 3y
Step 2: 4 * (7x + 3y) = 28x + 12y
Step 3: 28x + 12y + x = 29x + 12y
Step 4: 29x + 12y – (x – y) = 29x + 12y – x + y = 28x + 13y