1) x^2- 14x + 33 =0
D = 196-132=64
√D=√64=8
(14+8)/2=11; (14-8)/2=3
2) -3x^2 + 10x - 3=0
D=100-36=64
√D=√64=8
(-10+8)/(-6) = 1/3 ; (-10-8)/(-6) = 3
<span>x+ у = 6
5x + 2y=9
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</span>из первого y = 6 - x
из второго 5x + 2(6-x)=9
5x +12 -2x = 9
3x = -3
x =-1
y = 6 - (-1) = 7
ответ (-1; 7)
SinA=√(1-cos²A)=√(1-9/13)=√(4/13)=2/√13
AB=BC/sinA=6:2/√136*√13/2=3√13
AC=√(AB²-BC²)=√(117-9/13)=18√(42/13)=234√42/13
Х+5у=7⇒х=7-5у
3х+2у=-5
а)3*(7-5у)+2у=-5
21-15у+2у=-5
13у=26
у=2
б)х=7-5*2
х=-3