Solving linear inequalities
Solve like an equation, but flip the inequality sign when you multiply or divide by a negative. 2x − 3 > 7 gives x > 5.
Try it: Solve −2x < 8.
Show answer
x > −4, because dividing by −2 flips the sign.
Grade 9
Lessons by subject. Read the lesson, try the question, then check your answer.
Topics follow the Georgia Standards of Excellence, the state's current standards (they replaced the older Common Core Georgia Performance Standards). This is an unofficial study aid, not a Coffee County Schools resource. Your teacher's pacing guide and textbook come first. Official standards: georgiastandards.org.
Math
Linear Equations and Inequalities
Slope from two points
Slope = (y₂ − y₁) ÷ (x₂ − x₁). For (1, 2) and (3, 8), the slope is 6 ÷ 2 = 3.
Try it: Find the slope through (0, 1) and (4, 9).
Show answer
2.
Systems and Exponents
Solving systems by substitution
Substitute one equation into the other. For y = 2x and x + y = 9, x + 2x = 9, so x = 3 and y = 6.
Try it: Solve y = x + 1 and 2x + y = 7.
Show answer
x = 2, y = 3.
Exponent rules
Add exponents when multiplying powers with the same base, and multiply them for a power of a power: x³ · x⁴ = x⁷ and (x²)³ = x⁶.
Try it: Simplify x⁵ · x².
Show answer
x⁷.
Geography
Tools of Geography
The five themes
Geographers use five themes: location, place, human-environment interaction, movement, and region.
Try it: Which theme asks how people change their environment?
Show answer
Human-environment interaction.
Map projections
Flat maps distort Earth. The Mercator projection keeps directions accurate but stretches areas near the poles, making Greenland look huge.
Try it: What problem do all flat maps share?
Show answer
They distort size, shape, distance, or direction.
Population and Culture
Population density
Population density = people ÷ area. 1,000 people in 50 square miles is 20 people per square mile.
Try it: A town has 3,000 people in 10 square miles. What is its density?
Show answer
300 people per square mile.
Urbanization and migration
Urbanization is the growth of cities as people move from rural areas. Push and pull factors explain why people migrate.
Try it: Is moving for better schools a push or a pull factor?
Show answer
A pull factor.
Language Arts
Reading Literature
Theme, symbols, and character
Authors use symbols (objects that stand for ideas) and character change to develop a theme.
Try it: What is a symbol in literature?
Show answer
An object, person, or place that stands for a larger idea.
Structure and craft
A flashback shows earlier events, and foreshadowing hints at what will happen later.
Try it: Which technique gives hints about future events?
Show answer
Foreshadowing.
Writing
Thesis statements
A thesis states your main argument in one or two sentences and previews your reasons.
Try it: Is Dogs are animals a strong thesis?
Show answer
No. It states a fact, not an arguable claim.
Using and citing evidence
Introduce quotes, explain them, and give credit. In MLA style, a parenthetical citation gives the author and page, like (Smith 42).
Try it: Why do writers cite sources?
Show answer
To give credit, to let readers find the source, and to avoid plagiarism.