0.6x+1.2-1.2x+1.8=4x-20
-0.6x+3=4x-20
-4.6x=-23
x=0.2
а) <span>(sint+cost)^2/(1+2sin t cos t)=(sin^2t+2sint cost+cos^2t)/(1+2sint cost)=(1+2sint cost)/(1+2sint cost)=1</span>
<span>b) (<span>1-2sin t cos t)/(cos t-si t)^2=(1-2sint cost)/(cos^2t-2sint cost+sin^2t)=(1-2sint cost)/(1-2sint cost)=1</span></span>
a) <span> cos^2 t/1-sin t -sint t=1 </span>
((1-sin^2t)-sint(1-sint))/(1-sint)=1
(1-sin^2t-sint+sin^2t)/(1-sint)=1
(1-sint)/(1-sint)=1
Ну как сдал вчера контрольную?
1/(sin^2 x) + 1/(cos(7pi/2 + x)) = 2
1/(sin^2 x) + 1/(cos(4pi-pi/2+x)) = 2
1/(sin^2 x) + 1/(cos(pi/2-x)) = 2
1/(sin^2 x) + 1/(sin x) = 2
Умножаем всё на sin^2 x
1 + sin x = 2sin^2 x
2sin^2 x - sin x - 1 = 0
(sin x - 1)(2sin x + 1) = 0
sin x = 1; x = -pi/2 + 2pi*k
sin x = -1/2; x = -pi/6 + 2pi*n; x = 7pi/6 + 2pi*n
Корни на промежутке [-5pi/2; -pi]: x1 = -5pi/2; x2 = -13pi/6
2(3 - y) = 3(2y + 7)
6 - 2y = 6y + 21
-2y - 6y = 21 - 6
-8y = 15
y = 15 : (-8)
y = -15/8
Ответ: -15/8