Constant, linear, square and cube graphs

Constant, linear, square and cube graphs

Secondary 4
TGM Original — E Math Summary Notes (4052), 2026 editorial manuscript

The power family \(y=ax^n\), with nonzero constant \(a\), includes exponents \(0,1,2,3\). For \(n=0\), use the constant function \(y=a\), including at \(x=0\); no evaluation of \(0^0\) is needed.

PowerShape for positive coefficient
\(n=0\)Horizontal line
\(n=1\)Straight line through the origin
\(n=2\)Upward-opening parabola, symmetric about the y-axis
\(n=3\)Increasing cubic curve through the origin

Example

The sketches show \(y=x^2\) and \(y=x^3\). At \(x=-2\), their values are \(4\) and \(-8\), respectively. The square graph has equal outputs at opposite inputs; the cube graph has opposite outputs.

Multiplying by a negative coefficient reverses every output sign, reflecting the graph in the horizontal axis. The graph of \(y=-x^2\) therefore opens downward; \(y=-x^3\) decreases from left to right.

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