x(в квадрате) + 2X -15 =0
D= 4-4*1*(-15) =4+60=64=8(в квадрате)
X1= (-2+8) /2 = 3
X2 = (-2-8) /2 = -5
Ответ : X1 = 3; X2 = -5.
1) (x-y)+y=-3+2x
x=-3+2x
x=3
y=2*3=6
2) (2x-y)+y=-4+3x
2x=-4+3x
x=4
y=3*4=12
1) √3ctg(3π/2 - x) = - √3
tgx = - 1
x = - π/4 + πk, k∈Z
2) 1 - 2*sin^2(π/2 - x) = 0
cos^2x = 1/2
a) cosx = - √2/2
x = (+ -)arccos(- √2/2) + 2πn, n∈Z
x = (+ -)*(π - arccos(√2/2) + 2πn, n∈Z
x = (+ -)*(π - π/4) + 2πn, n∈Z
x1 = (+ -)*( 3π/4) + 2πn, n∈Z
b) cos^2x = √2/2
x = (+ -)arccos(√2/2) + 2πn, n∈Z
x2 = (+ -)*( π/4) + 2πn, n∈Z
3) ctg(3π/2 + x)*ctg(x - π/2) = 1
tgx*tgx = 1
tg^2x = 1
a) tgx = - 1
x = - π/4 + πk, k∈Z
b) tgx = 1
x = π/4 + πn, n∈Z