<span>6sin ^ 2x-4sin2x +1 = 0
6sin ^ 2x-8sinxcosx + (sin^2x+cos^2x) = 0
7sin ^ 2x-8sinxcosx + соs^2x = 0 - delim na cos^2x
7tg^2x-8tgx+1=0
Замена: tgx=a
7a^2-8a+1=0
a1=1;a2=1/7
Reshaem 2 uravneniya:
1)tgx=1
x=arctg1+Pin=Pi/4+Pin;
2)tgx=1/7
x=arctg1/7+Pin; (n принадлежит Z)
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1)(х-5)×(х+5)=х^2-25 2)(8+у)×(у-8)= -64+у^2 3)(10-к)×(к+10)=100-к^2 4)(a+2/3b)×(a-2/3b)=a^2+4/9b^2 5)(4/9x-y)×(y+4/9x)= -y^2+16/81x^2 6)(4/15n-m)×(m+4/15n)= -m^2+16/225n^2 7)(9x-5y)×(9x+5y)= 81y^2-25y^2 8)(-4a+3b)×(3b+4a)= -16a^2+9b^2 9)(13k-2b)×(2b+13k)= 169k^2-4b^2 10)(5/4c+3/7d)×(3/7d - 5/4c)= -25/16c^2+9/49d^2 11)(1/3x-3y)×(3y+1/3x)= -9y^2+1/9x^2 12)(1/5a+1/9b)×(1/9b - 1/5a)=1/25a^2+1/81b^2