Algebra 4

2 marks · Normal

Write down whether each of the following is an expression, an equation, or an identity. (i) 5y + 6 (ii) 7x − 2 = 3 (iii) 2(a + 1) = 2a + 2

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Must show: expression: 5y + 6, equation: 7x − 2 = 3, identity: 2(a + 1) = 2a + 2

Also accept: (i) expression (ii) equation (iii) identity

Common mistakes: Calling 5y+6 an equation; Not recognising the identity form

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Marking points

B1 · 1 mark · Correctly identifies all three: expression, equation, identity.

B2 · 1 mark · One or two correct with no incorrect, or two correct with one blank.

Worked solution

i) 5y + 6 is an expression (no equals sign). ii) 7x − 2 = 3 is an equation (can be solved for x). iii) 2(a + 1) = 2a + 2 is an identity (true for all a).