Question

Сократить дробь (a+2)/((a^2)-7a-18)

Answer 1

a^2 - 7a - 18 = ( a - 9 )( a + 2 )
D = 49 + 72 = 121
√ D = 11 
a1 = ( 7 + 11 ) : 2 = 9 
a2 = ( 7 - 11 ) : 2 = - 2 
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( a + 2 ) / ( ( a - 9 )( a + 2 )) = 1 / ( a - 9 )