X^2 - 16X + 63 = ( X - 9)*( X - 7 )
D = 256 - 252 = 4 ; √ D = 2
X1 = ( 16 + 2 ) : 2 = 9
X2 = ( 16 - 2 ) : 2 = 7
3X^2 - 5X - 2 = 3 * ( X - 2 ) * ( X + 1 )
D = 25 + 24 = 49 ; √ D = 7
X1 = ( 5 + 7 ) : 6 = 2
<span>X2 = ( 5 - 7 ) : 6 = - 1/3</span>
D = b² - 4ac = 49 -5*4*2 = 49 - 40 = 9 = 3² > 0
Будет 7,4 года. надо 11 умножить на две трети