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Find the minimum of x+t²/x for x>0.

Read the idea, work independently, then explain what changed.

TOPIC 01

Derivatives and their applications: mixed review

A mixed assessment: identify the method, justify it and revise your reasoning.

What you will be able to explain

  • Connect the chapter skills without relying on the order of the exercises.

Try it. Leave your reasoning visible.

Use one hint at a time. A correction explains what changed, not just the final answer.

01 / Transfer#Your turn

Find the minimum of x+t²/x for x>0.

t=34t=34
  • A critical point needs a sign or second-derivative check; closed-interval global extrema also require endpoints.
Skills and prerequisite lessons

Working and explanation

BUILD THE REASONING

Hint 1
Differentiate the specified function and substitute only after differentiating.
Hint 2
Use this intermediate relation.
f′(x)=1−t2/x2f\prime(x)=1-t^2/x^2
Worked solution
  1. Differentiate the specified function and substitute only after differentiating.

  2. Apply the stated relation and retain its conditions.

    f′=0⇒x=34f'=0\Rightarrow x=34
  3. Apply the stated relation and retain its conditions.

    f′′=2312/x3>0f''=2312/x^3>0
  4. Apply the stated relation and retain its conditions.

    f(34)=68f(34)=68
  5. The negative critical solution is outside the positive domain.

The requested value is 68.

Checks and common pitfalls: The negative critical solution is outside the positive domain.

Think first. Reveal a hint when the class is ready.

Focus on one question

Teacher preparation and assessment

Question sequence

  • Ask students to name the relevant condition before calculating.

Board plan

  • Compare valid methods and annotate their conditions.

Anticipated thinking

  • A correct final value may still hide a missing assumption.

Assessment checklist

  • Check the method, conditions, reasoning and interpretation separately.

No sign-in. Work stays in this browser. Export before clearing browser data. Written reasoning is assessed with a checklist.

Curriculum and source notes ↗