Algebra Master — Algebra Basics worksheet for Grade 8.
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An equation is like a balanced scale. Whatever you do to one side must be done to the other to keep it balanced and true. If you subtract 5 from just the left side, the equation is no longer equal. This principle, called the properties of equality, keeps the equation valid as you simplify it to find the variable's value.
Use the reverse order of operations (PEMDAS backwards). First, undo addition and subtraction (moving further from the variable), then undo multiplication and division (moving closer to the variable). For example, in 3x + 7 = 16, subtract 7 first, then divide by 3. This systematic approach prevents errors and confusion.
When a variable appears on both sides, you're looking for the value that makes both expressions equal. Start by moving all variables to one side using addition or subtraction. For example, in 2x + 5 = x + 12, subtract x from both sides to get x + 5 = 12, then solve normally. This consolidates the variable so you can isolate it.
Substitute your answer back into the original equation for the variable and calculate both sides. If both sides equal the same number, your answer is correct. For instance, if you solved 3x + 2 = 11 and got x = 3, check: 3(3) + 2 = 9 + 2 = 11 ✓. This verification strategy is the most reliable way to catch your own mistakes.
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Guess-and-check works for simple equations but fails with harder ones, especially when answers aren't whole numbers or when equations come from real-world contexts where guessing is impractical. Systematic algebraic solving is efficient, reliable, and works for any equation—it's a powerful tool that will help you in advanced math, science, and engineering.