X = -5, y = 1; x = 33, y = 20
Нууууу, у меня не 2. Скачай 《photomatch》 и решай без проблем
(3х-а)*2+(4х+1)*2=(5х-1)*2
9x^2-6ax+a^2+16x^2+8x+1=25x^2-10x+1
9x^2-6ax+a^2+16x^2+8x+1-25x^2+10x-1=0
-6ax+a^2+18x=0
1) tg 55 - tg 35 = 2tg 20
sin (55 - 35) : (cos 55 · cos 35) = 2tg 20
sin 20 : [0.5(cos (55 -35) + cos (55 + 35)] = 2tg 20
2sin 20 : (cos 20 + cos 90) = 2tg 20
2sin 20 : cos 20 = 2tg 20
2tg 20 ≡ 2tg 20
2) (2sin α - sin 2α) : (2sin α + sin 2α) =
= (2sin α - 2sin α ·cos α) : (2sin α + 2sin α · cos α) =
= [2sin α (1 - cos α)] : [2sin α (1 + cos α) =
= (1 - cos α) : (1 + cos α) =
= 2sin² 0.5α : 2cos² 0.5α =
= 2tg² 0.5α
3) 1 - tg π/16 · tg 3π/16) : (tg π/16 + tg 3π/16) =
= (tg π/16 + tg 3π/16) : [(tg π/16 + tg 3π/16) · tg (π/16 + 3π/16) =
= 1 : tg 4π/16 = 1 : tg π/4 = 1 : 1 = 1