A model R(x) = 84 / (x - 5) reports an output of 12. What input x produced it?
Answer
12
Reasoning Strategy
Find the shifted denominator first, then undo x - 5.
AI Support Preview
Keep x - 5 grouped as one denominator quantity.
Public Practice Guide
Use this guide to see the type of reasoning MathRoutine expects for grade 10 rational and radical equations with answers. The goal is not worksheet volume; it is helping students read the situation, choose a model, and explain why the answer fits.
What Students Practice
Reasoning Patterns
Sample Problems
These grade-specific examples show the kind of student-visible reasoning MathRoutine is designed to support: identifying the important quantities, choosing the right structure, and checking the final answer against the story.
A model R(x) = 84 / (x - 5) reports an output of 12. What input x produced it?
Answer
12
Reasoning Strategy
Find the shifted denominator first, then undo x - 5.
AI Support Preview
Keep x - 5 grouped as one denominator quantity.
A team shares a fixed $960 equipment cost equally among x players. The cost per player is modeled by c(x) = 960 / x. How many players are needed for the cost to be $40 per player?
Reasoning Strategy
Set 960 / x = 40 and solve for the denominator quantity.
AI Support Preview
Keep x as the number of players and reject x = 0 as impossible.
The stopping distance of a cart is modeled by d(v) = sqrt(20v), where v is speed in meters per second. What speed gives a stopping distance of 10 meters?
Reasoning Strategy
Set the radical expression equal to 10, square both sides, then solve.
AI Support Preview
Require a check after squaring to avoid extraneous reasoning.
A machine's average cost after producing x parts is A(x) = 12 + 480 / x. How many parts must be produced for the average cost to be $20?
Reasoning Strategy
Subtract the fixed per-part amount first, then solve the rational equation.
AI Support Preview
Separate the constant cost floor from the shared setup cost.
A water sensor uses r(x) = 180 / (x - 4). What output does it report when x = 13?
Reasoning Strategy
Simplify the denominator first, then divide.
AI Support Preview
Flag x - 4 as the hidden denominator step before any division happens.
A calibration model is m(x) = 7 + sqrt(x + 11). What output is reported when x = 53?
Reasoning Strategy
Add inside the radical, take the square root, then add the outside value.
AI Support Preview
Separate inside-radical work from the final outside addition.
A printer queue model is q(x) = 96 / (x - 5). What input x gives an output of 12?
Reasoning Strategy
Work backward to find the denominator, then undo the shift.
AI Support Preview
Show why x cannot be treated as the denominator directly.
A model R(x) = 120 / (x - 4) gives output 15. What input x produced it?
Answer
12
Reasoning Strategy
Work backward to find the denominator, then undo the shift.
AI Support Preview
Treat x - 4 as one denominator quantity.
Keep Practicing
Practice 1000+ more problems with grade-fit AI support.
Practice Ladder
Modeled after Algebra 1/Algebra 2 workbook expectations: interpret a function or equation in context, solve or compare it, then justify the meaning of the answer.
Connect the equation form to the real situation before calculating.
Evaluate, reverse, or compare the model while tracking restrictions and units.
Use the result to answer the actual question, not just the algebraic expression.
Assessment Signals
A guide is useful only if it clarifies what teachers and parents should look for in student work. MathRoutine tracks these signals during practice instead of treating every miss as the same mistake.
Common Mistakes
Learning Loop
A strong word problem platform should not only say right or wrong. It should notice the pattern: missed unit rate, ignored leftover, reversed comparison, wrong base percent, or equation setup error.
1
Attempt
2
Diagnosis
3
Next practice
Diagnosis Examples
Each word problem should create evidence about setup, calculation, vocabulary, hidden quantities, or final-question confusion. These examples show what MathRoutine is designed to separate after an attempt.
If the attempt shows
The student clears a denominator and accepts an excluded input.
Likely diagnosis
Domain restrictions are not checked after solving.
Next practice
Use rational model problems that ask students to name invalid inputs first.
If the attempt shows
The student squares both sides and keeps an extraneous radical solution.
Likely diagnosis
Inverse-operation solving is not followed by substitution check.
Next practice
Practice radical equations where checking eliminates a tempting answer.
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