Question

daca a²-b²=15,iar a+b=-3?calculati a-b​

Answer 1

Răspuns:

a+b=-3 => a=-3-b => a=-b-3

(-b-3)²-b²=15

b²-2•(-b)•3+9-b²=15

b² se reduc

=> 6b+9=15

=> 6b=15-9

=> 6b=6

=> b=1

a+b=-3 => a+1=-3 => a=-3-1=-4

=> a-b=-4-1=-5