﻿ ﻿AN IMPORTANT SYMBOL USED IN THIS BOOK - Important Tactics - SAT SUBJECT TEST MATH LEVEL 1

## CHAPTER 1Important Tactics • Use of the Calculator

• Backsolving

• Extra Variables

• Proper Use of Diagrams

• Roman Numeral Problems

• Eliminating Choices

As a general rule, students should take SAT Subject Tests in those subjects in which they excel and avoid taking them in subjects that are difficult for them. Consequently, almost all students who take the Math 1 test have good averages in math (typically at least a B+).

### AN IMPORTANT SYMBOL USED IN THIS BOOK

Important

Know what the symbol ⇒ means in this book.

In the solutions of examples, exercise sets, and questions on the Model Tests, the symbol ⇒ is used to indicate that one step in the solution follows immediately from the preceding one and that no explanation is necessary. You should read

“2x = 12 ⇒ x = 6” as

“2x = 12, which implies that x = 6,” or, “since 2x = 12, than x = 6.”

The solution to the following problem illustrates the use of the symbol ⇒:

What is the value of 3x2 – 7 when x = –5?

x = –5 ⇒ x2 = (–5)2 = 25 ⇒ 3x2 = 3(25) = 75 ⇒ 3x2 – 7 = 75 – 7 = 68.

When the reason for a step is not obvious, ⇒ is not used; rather, an explanation is given, often including a reference to a KEY FACT. In many solutions, some steps are explained, while others are linked by the ⇒ symbol, as in the following example: In the diagram above, if w = 10, what is the value of z?

• By KEY FACT H1, w + x + y = 180.

• Since AC = AB, by KEY FACT H3, x = y.

• Therefore, w + 2y = 180 ⇒ 10 + 2y = 180 ⇒ 2y = 170 ⇒ y = 85.

• Finally, since by KEY FACT G2, y + z = 180, we have 85 + z = 180 ⇒ z = 95.

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