Finding the Mean from a Frequency Table
Multiply each value by its frequency, add the products, then divide by the total frequency.
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Topic archive
Category: Algebra
Turning a Recurring Decimal into a Fraction
A short algebra trick turns recurring decimals into exact fractions instead of rounded approximations.
Read the explanation →Elimination or Substitution? How to Choose the Faster Method
There is no need to force one method every time. A quick look at the coefficients usually tells you which route will be shorter.
Read the explanation →Graph or Algebra? Choosing the Best Way to Solve Simultaneous Equations
Graphs show the idea well, but algebra is better when you need an exact intersection rather than an estimate.
Read the explanation →Substituting into a Formula Without Bracket Mistakes
Write the formula first, then replace variables carefully with brackets, especially when a value is negative.
Read the explanation →Changing the Subject of a Formula One Step at a Time
Treat formula rearrangement like solving an equation: isolate the target letter using inverse operations.
Read the explanation →Why the Inequality Sign Flips When You Multiply by a Negative
The sign reverses because the order of numbers changes when every value is multiplied by a negative.
Read the explanation →Collecting Like Terms Without Mixing Unlike Ones
x terms go with x terms, y terms go with y terms, constants go with constants, and different variables do not mix.
Read the explanation →How to Solve Equations with Brackets on Both Sides
The safest order is expand first, tidy both sides, move variable terms together, then solve.
Read the explanation →Why Does a Term Change Sign When You Move It Across an Equation?
Terms do not magically change sign. What really happens is that you add or subtract the same amount on both sides of the equation.
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