Algebra · real student question

Make h the subject of h/(4p) = p - 5k, expanding any brackets in your answer.

Question

Make hh the subject of

h4p=p5k.\frac{h}{4p}=p-5k.

Expand any brackets in your answer.

Step-by-step solution

  1. Identify what is currently attached to h. On the left, hh is divided by 4p4p. To free it, apply the inverse operation to both sides: multiply by 4p4p.

  2. Multiply both sides by 4p. Keep the whole right-hand side in brackets — this is where the second term usually gets lost:

    h=4p(p5k).h=4p\left(p-5k\right).

  3. Expand the bracket as instructed. The factor 4p4p multiplies each term inside:

    4pp=4p2,4p(5k)=20pk.4p\cdot p=4p^{2},\qquad 4p\cdot(-5k)=-20pk.

  4. Write the final rearranged formula.

    h=4p220pk.h=4p^{2}-20pk.

    Answering 4p25k4p^2-5k — multiplying only the first term — is the classic error the instruction 'expand any brackets' is designed to expose.

  5. Check by reversing. Divide the answer by 4p4p:

    4p220pk4p=4p24p20pk4p=p5k \frac{4p^{2}-20pk}{4p}=\frac{4p^{2}}{4p}-\frac{20pk}{4p}=p-5k\ \checkmark

  6. Test with numbers. Take p=2p=2 and k=1k=1. The original right side is 25=32-5=-3, so hh should be 4(2)(3)=244(2)(-3)=-24. The formula gives 4(4)20(2)(1)=1640=244(4)-20(2)(1)=16-40=-24 ✓.

Answer

h=4p220pkh=4p^{2}-20pk

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