1) 2 1/2 + 1 3/4 = 2 2/4 + 1 3/4 = 3 5/4 = 4 1/4
2) 6 2/3 + 4 4/5 = 6 10/15 + 4 12/15 = 10 22/15 = 11 7/15
3) 4 * 4 1/4 = 4 * 17/4 = 17
4) 11 7/15 : 2 = 172/15 * 1/2 = 86/15 = 5 11/15
5) 17 - 5 11/15 = 16 15/15 - 5 11/15 = 11 4/15
5х-3у=19
х-2у=1. *(-5)
5х-3у=19
-5х +10у=-5
7у=14
у=2
х-2*2=1
х=6
Ответ: (6;2)
D = 2a*2a + 4a(a-2)=0
4a^2 + 4a^2-8a =0
8a^2 - 8a =0
8a (a - 1) = 0
1. 8a = 0 a = 0
<span>2. a - 1 = 0 a = 1</span>