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Substitution

Substitution. Algebraic expressions are very often used to describe a situation in general terms. This means that the expression has a variable that can change and the value of the expression depends on the input for this variable. Substitution means replacing a variable with a number.

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Substitution

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  1. Substitution

  2. Algebraic expressions are very often used to describe a situation in general terms. This means that the expression has a variable that can change and the value of the expression depends on the input for this variable.

  3. Substitution means replacing a variable with a number. You then work out the value of the resulting expression using the correct order of operations (BEDMAS). So what does Substitution mean? Algebraic expressions are very often used to describe a situation in general terms. This means that the expression has a variable that can change and the value of the expression depends on the input for this variable.

  4. Example Let us think that the formula tells a farmer how many cows he can have where is the number of paddocks he has. How many cows could he have if he had 3 paddocks? How about 12? Is there a limitation to this rule? Algebraic expressions are very often used to describe a situation in general terms. This means that the expression has a variable that can change and the value of the expression depends on the input for this variable.

  5. More examples If , and find the values of these expressions: Algebraic expressions are very often used to describe a situation in general terms. This means that the expression has a variable that can change and the value of the expression depends on the input for this variable. 3 4 10 -3

  6. What you need to be careful with! • Using ‘hidden brackets’ • e.g. If p =-3 and q=6, then for • Negative numbers • e.g. For • Note: use brackets around the negative number (-3)

  7. Use formula and substitution applied to word (application) problems Fish and Chips order F = Number of pieces of Fish C = Number of scoops of Chips Our formula (rule) is $ = 2F + 1.5C where $ = Total Cost spent 1) How much does one piece of fish cost? 2) How much does one scoop of chips cost? 3) How much does 2 fish and 2 scoops of chips cost? 4) 4 fish and 3 scoops? 5) If I had spent $9.00 what did I buy? 6) If I spent $15.00 what could I buy?

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