tg a + tg b = sin a /cosa + sin b / cos b = (sin a * cos b + sin b * cos a) / (cos a * cos b) =
A) -12xyz-13zxy-yzx+25xyz = -xyz
б) 11x-13x+1,7-0,7x = 1,7-2,7x
в) -x+2u-3u+5x-6x-7u = -2x-14u
г) x²·x+x³+7x+x = x³+x³+8x = 2x³+8x
X²-9y²+x-3y=(x²-9y²)+(x-3y)=(x²-(3y)²)+(x-3y)=(x-3y)(x+3y)+(x-3y)=
=(x-3y)(x+3y+1)
3-4(1-6)=2(3x+4) 3-4+24x=6x+8 24x-6x=8-3+4 18x=9 x=9/18 x=1/2 x=0,5