Cos765=cos(720+45)=cos45=√2/2
sin19π/6=sin(3π+π/6)=sin(π+π/6)=-sinπ/6=-1/2
а) <span> (√6+<span> √10)*2<span> √2-2<span> √12=2<span> √12+2<span>√20-2<span>√12=<span> 2√20</span></span></span></span></span></span></span></span>
<span><span><span><span><span><span><span><span>б) (2√5-7)в квадрате+28√5=20-28√5+28√5=20</span></span></span></span></span></span></span></span>
A) <span>(z-7)(z+1)-(z+3)^2= z^2+z-7*z-7-(z^2+2*3*z+3^2)=z^2+z-7*z-7-z^2-6*z-9=
=-12*z-16</span>
4 - x^2 = - 3x
4 - x^2 + 3x = 0 /:(-1)
x^2 - 3x - 4 = 0
D = 9 + 16 = 25
x1 = (3 + 5)/2 = 8/2 = 4
x2 = (3 - 5)/2 = - 2/2 = - 1
Абсцисса точки B: x = 4