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Introduction to formulas

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Terms and expressions

Algebraic terms and expressions

In algebra, letters are used when numbers are not known.

Algebraic terms, like 2s or 8y, leave the multiplication signs out. So rather than '2 × s', write 2s, rather than '8 × y' write 8y.

A string of numbers and letters joined together by mathematical operations such as + and - is called an algebraic expression.

  • r + 2s means an unknown number 'r', plus 2 lots of an unknown number 's'.

Question

Q1. Say that 'g' is the cost of child admission, and 'k' is the cost of adult admission to the zoo.

a) How much does it cost for the Khan family of 3 children and 3 adults to visit the zoo?

b) Write an algebraic expression for the cost for the Norman family of 5 children and 4 adults to visit the zoo.

Answer

a) Cost for 3 children = 3g
Cost for 3 adults = 3k
Total cost = 3g + 3k

b) 5g + 4k

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