3x=π/4+2πn U 3x=3π/4+2πk
x=π/12+2πn/3 U x=π/4+2πk/3
0≤π/12+2πn/3≤2π
0≤1+8n≤24
-1≤8n≤23
-1/8≤n≤23/8
n=0⇒x=π/12
n=1⇒x=π/12+2π/3=9π/12=3π/4
n=2⇒x=π/12+4π/3=17π/12
0≤π/4+2πk/3≤2π
0≤3+8k≤24
-3≤8k≤21
-3/8≤k≤21/8
k=0⇒x=π/4
k=1⇒x=π/4+2π/3=11π/12
n=2⇒x=π/4+4π/3=19π/12
Сорян за подчерк, решала быстро
Ответ:
0,64х^2 + 2,08ху + 1,69у^2.
Объяснение:
(0,8х + 1,3y)^2 = (0,8х)^2 +2•0,8х•1,3у + (1,3y)^2 = 0,64х^2 + 2,08ху + 1,69у^2.
Решение4sin^2x-8sinx-5=0sinx = t4t² - 8t - 5 = 0D = 64 + 4*4*5 = 144t₁ = (8 - 12)/8t₁ = - 1/2t₂ = (8 + 12)/8t₂ = 3,5, 3,5 ∉ [ - 1;1] sinx = - 1/2x = (-1)^k * arcsin(- 1/2) + πk, k∈Zx = (-1)^(k + 1) * (π/6) + πk, k∈ZОтбор корнейk=-2; x=-2πk=-1; x=-π
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