1 ) We can solve the system:
4 x + 3 y = 54 / · ( - 3 )
3 x + 9 y = 108
- 12 x - 9 y = - 162
   3 x + 9 y = 108
 - 9 x = - 54              x = - 54 : ( - 9 ) = 6
 4 · 6 + 3 y = 54
 24 + 3 y = 54
 3 y = 54 - 24
 3 y = 30                  y = 30 : 3 = 10
  ( x , y ) = ( 6, 10 )
2 ) The greatest common monomial factor:
36 x^5 y^3 + 27 x^4 y = 9 x^4 y ( 4 x y^2 + 3 )
9 x^4 y.
3 ) Factor:
x² + 3 x - 18 = x² - 3 x + 6 x - 18 = x · ( x - 3 ) + 6 ( x - 3 ) =
= ( x - 3 ) · ( x + 6 )
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