Why is the inverse of a gradient -1/x?
Because the value, x and its inverse, -1/x should multiply together to give -1. This is proof that two lines are perpendicular (or having the same magnitude of gradient but opposite signs +/- ).
SR
Related Maths A Level answers
All answers ▸Given that y = (3x^4 + x)^5, find dy/dx using the chain rule.
Using trigonometric identities, show that (cos(x) + sin(x))^2=1+sin(2x)
How do I differentiate (x^2 + 3x + 3)/(x+3)
By writing tan x as sin x cos x , use the quotient rule to show that d dx ðtan xÞ ¼ sec2 x .