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Step-by-step explanation:
xy = -40 and x + y = 18
=> x(18 - x) = -40
=> 18x - x² = -40
=> x² - 18x - 40 = 0
=> (x - 20)(x + 2) = 0
=> x = 20 or x = -2.
The two numbers 20 and -2.
Answer:
let the numbers be x and y
[tex]xy = - 40 - - - (i) \\ x + y = 18 - - - (ii) \\ from \: (ii) \\ x = 18 - y \\ substitute \: for \: x \: in \: (i) \\ (18 - y)y = - 40 \\ 18y - {y}^{2} = - 40 \\ {y}^{2} - 18y - 40 = 0 \\ use \: the \: quadratic \: equation \: to \: get \: y \\ and \: y \: will \: give \: u \: x[/tex]
x = 20
hence y = 18-20
y = -2
or
x = -2
hence y = 18-(-2)
y = 20
The numbers are -2 and 20