Understanding how to substitute values into an expression is an essential skill when using graphs to estimate values of \(x\) and \(y\). There are no straight-line segments on a quadratic graph.

The gradient of \(y = 3x + 7\) is 3. Any line with a gradient ... c\), the question states that the graph goes through the point (2, 5). This means \(x = 2\) and \(y = 5\). Substitute these ...