One number is 4 less than twice a second number. find a pair of such numbers so that their product is as small as possible.

 For this case, the first thing we must do is define a variable.
 We have then:
 x: unknown number.
 First number: 2x - 4
 Second number: x
 The product of the numbers is:
 [tex] y = x (2x-4) [/tex]
 Rewriting:
 [tex] y = 2x ^ 2-4x [/tex]
 Deriving the equation we have:
 [tex] y '= 4x-4 [/tex]
 We equal zero and clear x:
 [tex] 4x - 4 = 0 x = 4/4 x = 1[/tex]
 Then, the first number is:
 [tex] 2x - 4 = 2 (1) - 4 = 2 - 4 = - 2 [/tex]
 Answer:
 First number: -2
 Second number: 1