a)252² - 251² =63504-63001=503
б)252²+2*252*48+48² = 63504+2*252*48+2304=63504+24192+2304=90000
А) 16х^2+24х+9-24х=16х^2+9
б) с^2+12с+36-с^2-12с= 36
в) 25х^2-4у^2-24х^2+6у^2= х^2+2у^2
г) 18с^2-9с^2+6с-1=9с^2+6с-1
2.74
[(3n+6)-7]/(n+2)=3- 7/(n+2)
n+2=7⇒n=5
n+2=-7⇒n=-9
Ответ n=5,n=-9
2.75
(3n²-16n+21)/(n-3)=3n-7
3n-7>0
3n>7
n>2 1/3
n={3,3,5,...}