Algebra 4
3 marks · HardA student writes the statement . State whether this is an expression, an equation, or an identity, and explain your reasoning.
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It is an identity because 2(x+3) always equals 2x+6 for any value of x.
Also accept: Identity, because both sides are equal for all values of x.
Common mistakes: Calling it an equation without explanation.; Not stating that both sides are equal for any x.
Show mark scheme and worked solution
Marking points
B1 · 1 mark · States the correct type: identity.
B2 · 1 mark · States that both sides are equal for any value of x.
B3 · 1 mark · Justifies with clear logical explanation relevant to all x.
Worked solution
It is an identity, because 2(x+3) expands to 2x + 6, which matches the right-hand side for any value of x.