Решение
<span>2х</span>²<span>+6х=0
2x*(x + 3) = 0
x</span>₁<span> = 0
x + 3 = 0
x</span>₂<span> = - 3</span>
3√80-2√20-√180=3√(4*20)-2√20-√(9*20)=3*2√20 - 2√20 - 3√20 = 6√20 - 2√20 - 3√20 = √20*(6-2-3) = √20
(2x+5)²- (2x-3)(2x+1)=4
4x²+20x +25 - (4x²+2x-6x-3)=4
4x²+20x+25-4x²+4x+3=4
24x+28=4
24x=4-28
24x= -24
x=-1
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(2*(-1)+5)²-(2*(-1) -3)(2*(-1)+1)=4
3²- (-5) * (-1)=4
9- 5=4
4=4
-6х+42+6х-3х(в квадрате)=39
-3х(в кадрате)=-3
х=1
По разности синусов:
sin(3x) - sin(17x) = 2*cos(10x)*sin(-7x) = -2cos(10x)*sin(7x) = 0
cos(10x) = 0, 10x = π/2 + πk, x = π/20 + πk/10, k∈Z
sin(7x) = 0, 7x = πk, x = πk/7, k∈Z