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a)

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The correct input is ({a}+{b}x)/({c}+{d}y) - the rest are incorrect and you should have chosen those.

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b)

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A correct input is ({b} + {a}y) / ({c} + {d}z). Also correct is ({a}y+{b}) / ({c} + {d}z) etc.

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c)

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A correct input is ({d}z + {b}) / ((x + {a})*(y + {c})).

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Note the denominator (the bottom of the ratio) has to have two brackets, i.e. ((x + {a})*(y + {c})) as otherwise the expression ({d}z + {b}) / (x + {a})*(y + {c}) is seen by the system as $\\displaystyle \\left(\\simplify[std]{({d} * z + {b}) / (x + {a})}\\right) (y + \\var{c})$

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d)

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A correct input is ({a} -({b}x + {c})*e ^ ( -{2}x)) / ((x + {2*b})*(y -{3*d})).

\n ", "rulesets": {"std": ["all", "!collectNumbers"]}, "parts": [{"prompt": "

Suppose you want to input the expression $\\displaystyle \\frac{\\var{a}+\\var{b}x}{\\var{c}+\\var{d}y}$.

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Choose which of the following inputs are incorrect?

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[[0]]

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After you have clicked Submit part, click on Show Feedback and you will be given more detail on your choices.

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This is the correct input, so your choice is wrong!", "{a}+{b}x/({c}+{d}y)
Good choice: the system thinks this is $\\simplify[std]{ {a}+{b}x/({c}+{d}y)}$ and not $\\simplify[std]{ ({a}+{b}x)/({c}+{d}y)}$.", "{a}+{b}x/{c}+{d}y
Good choice: the system thinks this is $\\simplify[std]{ {a}+{b}x/{c}+{d}y}$ and not $\\simplify[std]{ ({a}+{b}x)/({c}+{d}y)}$.", "({a}+{b}x)/{c}+{d}y
Good choice: the system thinks this is $\\simplify[std]{ ({a}+{b}x)/{c}+{d}y}$ and not $\\simplify[std]{ ({a}+{b}x)/({c}+{d}y)}$."], "showCorrectAnswer": true, "scripts": {}, "warningType": "none", "marks": 0, "choices": ["

({a}+{b}x)/({c}+{d}y)

", "

{a}+{b}x/({c}+{d}y)

", "

{a}+{b}x/{c}+{d}y

", "

({a}+{b}x)/{c}+{d}y

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Input the expression $\\displaystyle \\frac{\\var{b}+\\var{a}y}{\\var{d}+\\var{c}z}$. [[0]]

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Input the expression $\\displaystyle \\frac {\\var{d} z + \\var{b}} {(x + \\var{a}) (y + \\var{c})}$. [[0]]

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As a final challenge, input the expression $\\displaystyle \\simplify[std]{({a} -(({b} * x + {c}) * e ^ (( -{2}) * x))) / ((x + {2 * b}) * (y -{3* d}))}$. [[0]]

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This question shows you how to input algebraic fractions.

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You need to be careful to use brackets to show what goes into the numerator (top) and what into the denominator (bottom) of the fraction.

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Remember that you will see what the system thinks you have entered.

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Instructions on inputting ratios of algebraic expressions. Could link to calculator input.

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