Question

$x2 + 18x = 40$
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Answer 1

x2+ 18x =40

x2 + 18x -40=0

x2 -20x+2x-40=0

x(x-20) +2(x -20)=0

(x -20) (x+ 2 )=0

x=20 / x=-2

x=20

it's your answer my friend