Physics I / Graphs, approximation, and numerical sense
Practice question · Estimate

Use the linear approximation at x=16x=16 to estimate 16.4\sqrt{16.4}, then set the slider. (f(x)=xf(x)=\sqrt{x}, f(x)=12xf'(x) = \frac{1}{2\sqrt{x}}.)

Estimate on a scale from 3.9 to 4.2.

Hints
  1. Anchor at the friendly point: 16=4\sqrt{16} = 4, slope =1/8= 1/8.
  2. Follow the tangent: 4+0.484 + \frac{0.4}{8}.
Show the answer

4.05 (answers within ±0.015 count)

Why

16.44+0.05=4.05\sqrt{16.4} \approx 4 + 0.05 = 4.05 (true value 4.0497…). Near the anchor, the tangent line is the function to within a whisker, the idea behind every calculator’s first guess and every "small correction" in physics.

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