3sin^2x - 4sinxcosx + 5cos^2x = 2*1
<span>3sin^2x - 4sinxcosx + 5cos^2x = 2*(sin^2x+cos^2x)
</span><span>3sin^2x - 4sinxcosx + 5cos^2x = 2sin^2x + 2cos^2x
</span>3sin^2x - 2sin^2x - 4sinx*cosx + 5cos^2x - 2cos^2x = 0
sin^2x - 4sinx*cosx + 3cos^2x = 0 // : cos^2x ≠ 0
tg^2x - 4tgx + 3 = 0
(tgx - 3) (tgx - 1) = 0
tgx = 3
x = arctg(3) + pik, k ∈Z
tgx = 1
x = pi/4 + pik, k ∈Z
1) x=-25 y=-51 -51=2*-25-1 -51=-51 2) -37=-2*20+3 -37= -37
81x^2-18x+1=0
D=b^2-4ac
D=(-18)^2-4×81×1=324-324=0
x1;2= 18+0 18 1
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2×81 162 9
4x³y² - 6x²y³ = 2x²y²·(2x-3y)
2х²у² - общий множитель обоих слагаемых, так как
4х³у²=2·2·х·х²·у² и 6х²у³=3·2·х²·у²·у
S=6a²
a²=S/6
a=√(S/6)
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