distance (-1,8),(4,-2)
The distance is the norm of the difference of the points: the square root of the sum of the squared coordinate differences
Let's evaluate: ‖(4, -2) -(-1, 8)‖
ⅰ (4, -2) -(-1, 8) = (4 + 1, -2 -8)
‖(4 + 1, -2 -8)‖
ⓘ Start from 4 and move forward 1 on the number line: 4 + 1 = 5■Start from -2 and move back 8 more on the number line, away from zero: -2 -8 = -10
‖(5, -10)‖
ⅰ ‖(5, -10)‖ = 52 + (-10)2
52 + (-10)2
ⓘ Powers are computed before multiplications, additions and subtractions. An integer power is a repeated product: 52 = 5×5 = 25, (-10)2 = (-10)×(-10) = 100
25 + 100
ⓘ Parentheses are computed first: 25 + 100 = 125
125
ⓘ We look for the largest square dividing 125, 25 = 52, and take it out of the root: 125 = 25×5 = 25×5 = 5×5
▶Distance:   5×5
The numeric value of: 5×5 is:
5×≈ 2.2361
▷ ≈ 11.1803