How to add variables

ISEE Upper Level Quantitative Reasoning · Learn by Concept

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ISEE Upper Level Quantitative Reasoning › How to add variables

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1

Define . The graph of is a line with slope .

.

Which is the greater quantity?

(a)

(b)

(a) is the greater quantity

CORRECT

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

0

(b) is the greater quantity

0

(a) and (b) are equal

0

Explanation

, so .

, so, by definition, , or .

The graph of is a line through the point with coordinates and with slope . The equation of the line can be determined by setting in the slope-intercept form:

.

The equation of the line is , which makes this the definition of . By setting ,

.

Therefore,

2

; and are both positive.

Which is the greater quantity?

(a)

(b)

(b) is the greater quantity

CORRECT

(a) is the greater quantity

0

(a) and (b) are equal

0

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

0

Explanation

If ,

then

.

The absolute value of a negative number is its (positive) opposite, so

Also, if and are both positive, then is positive; the absolute value of a positive number is the number itself, so . Since , it follows that . Therefore,

Since is given to be positive,

.

and

3

Add:

CORRECT

0

0

0

0

Explanation

In order to simplify this expression, we will need to add like terms.

There is a lone positive three.

Combine all the terms.

The answer is:

4

Which of the following is the greater quantity?

(A)

(B)

(B) is greater

CORRECT

(A) is greater

0

(A) and (B) are equal

0

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

0

Explanation

(A) Substitute and evaluate, remembering that by order of operations, squaring precedes addition:

(B) Substitute and evaluate

(B) is greater

5

Which is the greater quantity?

(A)

(B)

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

CORRECT

(A) is greater

0

(B) is greater

0

(A) and (B) are equal

0

Explanation

Which quantity is the greater depends on the value of .

Case 1:

Then

and

Subsequently, (A) is greater

Case 2:

Then

and

Subsequently, (B) is greater

6

is a negative integer. Which is the greater quantity?

(A)

(B)

(a) is the greater quantity

CORRECT

(b) is the greater quantity

0

It cannot be determined which of (a) and (b) is greater

0

(a) and (b) are equal

0

Explanation

,

so

and

regardless of the value of .

7

is a negative number.

Which is the greater quantity?

(a)

(b)

(a) and (b) are equal

CORRECT

It cannot be determined which of (a) and (b) is greater

0

(a) is the greater quantity

0

(b) is the greater quantity

0

Explanation

The expressions and are each other's opposite, so they have the same absolute value. Therefore, regardless of the value of ,

.

8

is a negative integer. Which is the greater quantity?

(a)

(b)

(b) is the greater quantity

CORRECT

(a) is the greater quantity

0

It cannot be determined which of (a) and (b) is greater

0

(a) and (b) are equal

0

Explanation

Since

,

it follows that

and

regardless of the value of .

9

is a positive number.

Which is the greater quantity?

(a)

(b)

It cannot be determined which of (a) and (b) is greater

CORRECT

(a) is the greater quantity

0

(a) and (b) are equal

0

(b) is the greater quantity

0

Explanation

By examining two scenarios, we see that we cannot determine which is the greater quantity.

Case 1:

Then

and

This makes (a) the greater quantity.

Case 2:

Then

and

This makes (b) the greater quantity.

10

is a negative integer. Which is the greater quantity?

(A)

(B)

(b) is the greater quantity

CORRECT

(a) is the greater quantity

0

It cannot be determined which of (a) and (b) is greater

0

(a) and (b) are equal

0

Explanation

, so

and

is the greater quantity, regardless of .