Whats a priemiter of a rectangle whith length 12 m and width 5 m

Aman steps out of a plane at a height of 4,000m above the ground falls 2,000m very quickly and then opens his parachute and slowly falls the remaining 2000m to the ground what height above the ground would be the best choice for a reference point

Ineed me i stuck and i don’t want to get it wrong

Rewrite the following quadratic functions in intercept or factored form. show your work. f(x) = 3x^2 - 12