What is Substitution in Algebra for Year 7 NSW students?
In Algebra Substitution, a variable is replaced with a number. Basically, if the value of x is given, we substitute x with that number in the expression to find the result.
For example, if the expression is ‘x + 7′ and ‘x = 3′, then we substitute x with 3 to get ‘3 + 7′, which equals 10.
Why is Algebra Substitution Important for Year 7 NSW Students?
Algebra substitution forms the foundation for solving more complex algebraic problems. Once NSW students in Year 6 and Year 7 master substitution, they can confidently tackle linear equations with one, two, or more unknowns, as well as quadratic equations. It’s a key skill that builds the groundwork for success in high school mathematics and beyond.
How to perform Algebra Substitution?
- Identify the variable(s): Find the variables (letters) in the algebraic expression.
- Find the value: Look for the number that each variable represents.
- Replace: Carefully substitute each variable with its value.
- Calculate: Work out the answer using the correct order of operations (BODMAS/PEMDAS).
Examples of Algebra Substitution?
Three friends equally share the cost of a pizza. Each pays $10. They also buy a burger and a drink that cost twice as much as the pizza. How much does each friend pay in total?
Answer:
Let x be the cost of the pizza.
Each pays $10 → x = $30
Burger and drink cost = 2x = 2×$30 = $60
Total cost = x+2x =3x =3×$30=$90
Each friend pays = $90/3= $30
