число 24 это нок чисел 8 и 12
B1 = 49
b2 = 7
q = b2/b1 = 7/49 = 1/7
S = b1/(1 - q) = 49/(1 - 1/7) = 49/6/7 = 343/6
1) cos2x - 9cosx + 8 = 0
2cos²x - 1 - 9cosx + 8 = 0
2cos²x - 9cosx + 7 = 0
D = 81 - 4*2*7 = 25
cosx = t, I t I ≤ 1
2t² - 9t + 7 = 0
t₁ = (9 - 5)/4
t₁ = 1
t₂ = (9 + 5)/4
t₂ = 7/2 не удовлетворяет условию I t I ≤ 1
cosx = 1
x = 2πk, k∈Z
2) 3cosx + sinx = 0 делим на cosx ≠ 0
3 + tgx = 0
tgx = - 3
x = - arctg(3) + πn, n∈Z
3) 3sin2x + sinxcosx - 2cos2x = 0
3sin2x + 1/2sin2x - 2cos2x = 0
3,5* sin2x - 2cos2x = 0 делим на cos2x ≠ 0
3,5tg2x - 2 = 0
tg2x = 4/7
2x = arctg(4/7) + πn, n∈Z
x = (1/2)*arctg(4/7) + πn/2, n∈Z
Ответ:
(0;10) (-2;-4) (6;4) (-8;2)
Объяснение:
xy-3x+y-10=0
y(x+1)=3x+10
y=(3x+10)/(x+1)=(3x+3+7)/(x+1)=(3x+3)/(x+1)+7/(x+1)=3+7/(x+1)
3 целое число
x+1 должно быть делителем числа 7
x+1=1; x=0; y=3+7=10
x+1=-1; x=-2; y=3-7=-4
x+1=7; x=6; y=3+1=4
x+1=-7; x=-8; y=3-1=2
ответ: (0;10) (-2;-4) (6;4) (-8;2)