A letter is just a number in hiding
In x + 3 = 10, x is one particular number. Nothing mysterious — the job is to find out which one.
Class 6 to 12 · 80 games
Algebra, explained with pictures
Using a letter to stand for a number you do not know yet.
In everyday life: Working out how many are left in a box when you only know how many you took.
An equation balances, so do the same to both sides
Think of scales. Take 3 off the left and you must take 3 off the right, or it tips. That is the whole method for solving.
Substituting means putting the number back in
If x = 4, then 3x + 2 is 3 x 4 + 2 = 14. It also lets you check an answer: put it back and see if the equation is true.
A worked example
Solve 2x + 1 = 9.
x = 4
Take 1 off both sides to get 2x = 8. Halve both sides to get x = 4. Check: 2 x 4 + 1 = 9.
Words to know
- variable
- A letter standing for a number.
- equation
- A statement that two things are equal, with an = sign.
- substitute
- Replace the letter with its value.
In the games
You will pick the value that solves an equation and work out what an expression comes to for a given value.
Skills
- Variables, rules and expressions · Class 6
- Solve a one-step linear equation · Class 7
- Substitute into an expression · Class 7
- Equations with x on both sides · Class 8
- Algebraic identities and factorisation · Class 8
- Polynomials and the factor theorem · Class 9
- Linear equations in two variables · Class 9
- Roots of a quadratic · Class 10
- Zeros of a polynomial and its coefficients · Class 10
- A pair of linear equations in two variables · Class 10
- Relations and functions · Class 11
- Linear inequalities · Class 11
- Compose two functions · Class 12
- Linear programming · Class 12
By class
Class 6 algebra (8) · Class 7 algebra (10) · Class 8 algebra (18) · Class 9 algebra (14) · Class 10 algebra (12) · Class 11 algebra (12) · Class 12 algebra (6)
Practise algebra in Tivumo
No download, no account for your child. Classes 3 to 12, more than 1,000 games.