1)
(38²-28²): (47²-19²)=(38-28)(38+28) : (47-19)(47+19)=10*66 / 28*66 =10/28=5/24
2)
(53²-25²) : (79²-51²)=(53-25)(53+25) : (79-51)(79+51)=28*78/28*130=39/65
3)
(181²-61²) : (219²-77²)= (181-61)(181+61) : (219-77)(219+77)=120*242/142*296=
=15*121/71*37=1815/2627
4)
(200²-380²) : (420²-160²)= (200-380)(200+380) : (420-160)(420+160)= -180*580/260*580=-18/26=-9/13
а) 2х*(с-3) - у*(с-3) = (2х-у)*(с-3)
б) 5х*(3а+2b) - 7y*(2b+3a) = (3a+2b)*(5x-7y)
в) 8p*(7q+1)-1*(1+7q) = (1+7q)*(8p-1)
А) (7a- 1)(7a+ 1)<49a²
49a² - 1< 49a²
49a² - 49a²< 1
0<1
a- любое число, (-∞; +∞)
б) a²+ 15a+ 56>a(a+ 15)
a²+ 15a+ 56> a²+ 15a
a²+ 15a- a² - 15a> - 56
0> - 56
a- любое число, (-∞; +∞)