Shocked By How One Brightness Setting Can End Your Eye Strain Forever!

Shocked By How One Brightness Setting Can End Your Eye Strain Forever!
What if a single setting on your screen—yes, just one—could

Shocked By How One Brightness Setting Can End Your Eye Strain Forever!
What if a single setting on your screen—yes, just one—could
Time to return = \( \frac{150}{80} = 1.875 \) hours.
Total time = \( 2.5 + 1.875 = 4.375 \) hours.
Total distance = \( 150 \times 2 = 300 \) km.
Average speed = \( \frac{300}{4.375} \approx 68.57 \) km/h.
#### 150 km, 68.57 km/h
If the sum of the first \( n \) natural numbers is 210, find \( n \).
The formula for the sum is \( \frac{n(n+1)}{2} = 210 \).
Solving \( n(n+1) = 420 \).
\( n^2 + n - 420 = 0 \).
Using the quadratic formula, \( n = \frac{-1 \pm \sqrt{1 + 1680}}{2} \).