lt;br>- linear modelling | - *repeated content* | | [[Variation and Rates of Change A]] | - direct variation | - *repeated content* | ## Linear modelling - Determine the $y$-intercept and gradient of a straight line given in graphical form - Determine the equation of a straight line of the form $y=mx+c$ where $m$ is the gradient and $c$ is the $y$-intercept - Determine the $y$-intercept and gradient from the equation of a straight line - Construct a straight-line graph, with and without using graphing applications - Model linear relationships and interpret the features of those relationships in a variety of contexts, noting that the $y$-intercept is the vertical intercept and the gradient is the rate of change - Interpolate and extrapolate from a linear model in a practical context - Identify and describe the limitations of a linear model in a practical context - Use a spreadsheet to model a linear relationship in a variety of contexts ## Direct variation - Recognise that a direct variation relationship of the form $y=kx$ produces a straight-line graph - Explain that a direct variation relationship of the form $y=kx$ is a graph that passes through the origin with gradient $k$ being the constant of variation - Identify and represent direct variation of the form $y=kx$ from descriptions of situations in which one quantity varies directly with another quantity - Evaluate $k$ in the equations $y=kx$, given one pair of values for the variables, and use the resulting formula to find other values of the variables to solve problems in a variety of contexts - Graph and analyse equations of the form $y=kx$ to solve problems in a variety of contexts