Question

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$x \cdot y = 72$
$2x + y = 30$

Answer 1

Ola Sammy

x*y = 72
2x + y = 30 

y = 30 - 2x

x*(30 - 2x) = 72

30x - 2x² = 72

2x² - 30x + 72 = 0

x² - 15x + 36 = 0

delta
d² = 225 - 144 = 81
d = 9

x1 = (15 + 9)/2 = 24/2 = 12 , y1 = 30 - 24 = 6
x2 = (15 - 9)/2 = 6/2 = 3 , y2 = 30 - 6 = 24 

S = (x,y) , (12,6) , (3,24)