prismlearning.academy Logo
NEUR
N

The functions h and k are defined by the given equations.\(\mathrm{h(x) = 1 + |x^2 - 5x|}\)\(\mathrm{k(t) = |\frac{6}{t-1}| -...

GMAT Advanced Math : (Adv_Math) Questions

Source: Prism
Advanced Math
Nonlinear functions
HARD
...
...
Notes
Post a Query

The functions h and k are defined by the given equations.

\(\mathrm{h(x) = 1 + |x^2 - 5x|}\)

\(\mathrm{k(t) = |\frac{6}{t-1}| - t + 8}\), where \(\mathrm{t \neq 1}\)

If \(\mathrm{h(6) = d}\), where d is a constant, what is the value of \(\mathrm{k(d)}\)?

Enter your answer here
Solution

1. TRANSLATE the problem information

  • Given information:
    • \(\mathrm{h(x) = 1 + |x² - 5x|}\)
    • \(\mathrm{k(t) = |6/(t-1)| - t + 8}\), where \(\mathrm{t ≠ 1}\)
    • \(\mathrm{h(6) = d}\) (we need to find d first)
    • Find \(\mathrm{k(d)}\)
  • What this tells us: We have a two-step process - first evaluate h at x = 6, then use that result as input for function k.

2. SIMPLIFY to find h(6)

  • Substitute x = 6 into h(x):

\(\mathrm{h(6) = 1 + |6² - 5(6)|}\)

  • Calculate inside the absolute value first:

\(\mathrm{6² - 5(6) = 36 - 30 = 6}\)

  • Apply absolute value: \(\mathrm{|6| = 6}\)
  • Complete the calculation: \(\mathrm{h(6) = 1 + 6 = 7}\)
  • Therefore: \(\mathrm{d = 7}\)

3. SIMPLIFY to find k(7)

  • Substitute t = 7 into k(t):

\(\mathrm{k(7) = |6/(7-1)| - 7 + 8}\)

  • Calculate the fraction: \(\mathrm{6/(7-1) = 6/6 = 1}\)
  • Apply absolute value: \(\mathrm{|1| = 1}\)
  • Complete the calculation: \(\mathrm{k(7) = 1 - 7 + 8 = 2}\)

Answer: 2


Why Students Usually Falter on This Problem

Most Common Error Path:

Weak SIMPLIFY execution: Students make arithmetic errors when evaluating \(\mathrm{6² - 5(6)}\), calculating it as \(\mathrm{6² - 5 × 6 = 36 - 5 × 6 = 36 - 11 = 25}\) instead of \(\mathrm{36 - 30 = 6}\).

This leads to \(\mathrm{h(6) = 1 + |25| = 26}\), so \(\mathrm{d = 26}\), then \(\mathrm{k(26)}\) requires evaluating k at an unintended value, causing confusion and likely guessing.

Second Most Common Error:

Poor TRANSLATE reasoning: Students misunderstand the two-step nature of the problem, trying to find \(\mathrm{k(6)}\) directly instead of first finding \(\mathrm{d = h(6)}\), then evaluating \(\mathrm{k(d)}\).

This causes them to substitute 6 into the k function immediately, getting \(\mathrm{k(6) = |6/(6-1)| - 6 + 8 = |6/5| - 6 + 8 = 1.2 + 2 = 3.2}\), leading to confusion since this doesn't match typical answer formats.

The Bottom Line:

This problem tests your ability to follow a multi-step process systematically while handling absolute values correctly. The key is recognizing that you must complete the first function evaluation entirely before moving to the second function.

Rate this Solution
Tell us what you think about this solution
...
...
Forum Discussions
Start a new discussion
Post
Load More
Similar Questions
Finding similar questions...
Previous Attempts
Loading attempts...
Similar Questions
Finding similar questions...
Parallel Question Generator
Create AI-generated questions with similar patterns to master this question type.