algebriac expressions

• letters in algebra can represent any number
• A constant is a fixed numerical value that does not change.
• A variable is a letter that represents a value or quantity that may change.
• letters are variables and they are not definite numbers
• if there is no operation between the values, we assume it is multiplication
• when writing multiplication, the number is always in front of the letter
• for a value of 1 variable, just write y and not 1y
• we can evaluate expressions when we know the value of the unknown
• use substitution to replace expressions with numbers
• a formula is an expression that is equal to another expression
• in linear expressions, the highest power is 1
• like terms are terms that have the same variable.
• an expression is a combination of numbers,variables and functions
• a coefficient is a number that is in front of the unknown
• if it is a number it is both a coefficient and a constant number
• if it is a hybrid (eg. xy) it is not like terms with anything unless there is a coefficient
• we can only add or subtract like terms
• y squared is not like terms with y because you cannot add them together
• 2 constant numbers are like terms
• we cannot add numbers to linear expressions
• 2m + 1 -> simplest form
• like terms can be simplified but unlike terms cannot
• simplify like terms by grouping them together and taking the sign in front
• the process of removing brackets -> expansion
• factorisation -> opposite of expansion