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(i) To find \$f(\\var{x1})\$, you start at \$\\var{x1}\$ on the \$x\$-axis, go up or down until you reach the blue line, and then look at the \$y\$-coordinate. This \$y\$-coordinate is the answer.  In this question, after going up/down from \$\\var{x1}\$, we reach the \$y\$-coordinate \$\\var{y1}\$, so the answer is \$f(\\var{x1})=\\var{y1}\$.

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(ii) There are two options. The first option (which is not efficient) is trial-and-error: pick some random value of \$x\$ and determine \$f(x)\$. If \$f(x) = \\var{y2}\$, then your pick is the answer.  If not, then try a different value of \$x\$, hopefully getting closer and closer each time.   The second (and better) option is to 'work backwards' - we know what \$f(x)\$ should be, which means we know what the \$y\$-coordinate should be.  So start at \$\\var{y2}\$ on the \$y\$-axis, go left or right until you reach the blue line, and look at the \$x\$-coordinate. In this question, after going left/right from \$\\var{y2}\$, we reach the \$x\$-coordinate \$\\var{x2}\$, so this is the answer.  You can check this is correct: what is \$f(\\var{x2})\$? It is \$\\var{y2}\$, as we wanted!

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Random amount of vertifical shift for sake of variability.

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Coefficient of x^3

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Random amount of horizontal shift to create variability.

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{eqnline(a, hshift, vshift)}

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Above is the graph of some function \$f\$.

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What is \$f(\\var{x1})\$? [[0]]

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What value of \$x\$ do you need to get \$f(x) = \\var{y2}\$? [[1]]

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