How to subtract variables

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ISEE Upper Level Quantitative Reasoning › How to subtract variables

Questions 1 - 10
1

Simplify:

Explanation

To simplify this problem we need to combine like terms.

2

Simplify the following expression:

Explanation

Simplify the following expression:

We can only subtract variables with the same exponent.

In this case, we can only combine the first two terms.

To do so, keep the exponents the same and subtract the coefficients.

So our answer is:

3

Assume you know the values of all four variables in the expression

In which order do you perform the operations in order to evaluate the expression?

Divide, multiply, subtract

Multiply, divide, subtract

Subtract, divide, multiply

Subtract, multiply, divide

Multiply, divide, subtract

Explanation

Multiplication and division take precedence over subtraction in the order of operations, so these two operations are performed first. The two must be performed from left to right, so the division is worked first, followed by the multiplication. The subtraction is last.

4

Consider the expression:

Which of the following expressions must be equal in value to the above expression?

I)

II)

III)

I and III only

I and II only

I, II, and III

I only

III only

Explanation

The order of operations is as follows:

Exponents

Multiplication and division (left to right)

Addition and subtraction (left to right)

The expression

is therefore evaluated by multiplying, then dividing, then adding. The net result is that the product is added to the quotient .

If we examine (I), we see that, since the multiplication is in parentheses, it is worked first. The division is worked second, then the addition. The order of operations has not changed, so the expressions are equivalent.

If we examine (II), we see that the order of operations has changed so that the addition is worked first. We see through example that the expressions can have different values:

If we examine (III), we see that, since the division is in parentheses, it is worked first. The multiplication is worked second, then the addition. The upshot is the same as in the main expression, however - the product is added to the quotient . Therefore, the expressions are equivalent.

The correct response is (I) and (III)

5

is negative. Which of these quantities is the greater?

(A)

(B)

(B) is greater

(A) is greater

It is impossible to determine which is greater from the information given

(A) and (B) are equal

Explanation

,

So by the multiplication property of inequality, when each is multiplied by the negative number ,

.

Also,

,

so by the addition property of inequality,

or

This makes (B) greater.

6

Simplify:

Explanation

7

Simplify:

Explanation

To simplify this problem we need to combine like terms.

8

Simplify the following expression:

Explanation

Simplify the following expression:

Let's begin by subtracting the 12y

From here, our answer should be apparent:

So our answer is just 0

9

Simplify:

Explanation

10

When evaluating the expression

,

assuming you know the values of all five variables, what is the third operation that must be performed?

The leftmost subtraction

The rightmost addition

The rightmost subtraction

The leftmost addition

The middle subtraction

Explanation

In the order of operations, any operations in parentheses must be performed first - there are two, the leftmost addition and the middle subtraction. What remains are the leftmost subtraction, the rightmost subtraction, and the rightmost addition. Since additions and subtractions are performed from left to right, the next, or third, operation performed is the leftmost subtraction.

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