=a^2+25+10a+24+4a/(a+7)^2=1
a^2+14a+49/(a+7)^2=1
(a+7)^2/(a+7)^2=1
1=1
тождество верно
) f (0.5)=16-0.25=15.75
f (-3)=16-9=7
Б) 16-x^2=0
X^2=16
X=+-4
(6·9+7·3+8а+9·5)/(9+3+а+5) = 7,2
(54+21+8а+45)/(17+а) = 72/10
(120+8а)/(17+а) = 36/5
(30+2а)/(17+а) = 9/5
5(30+2а) = 9(17+а)
150+10а = 153+9а
а = 3