=3ab×18a^(3)×b^(3)=51a^(4)b^(4)
<span>(х-4)<em>во2степени</em> - 2(х+1) (х+4)=x<em>во2степени</em>+16-8x-2(x<em>во2степени</em>+4x+x+4)=x<em>во2степени</em>+16-8x-2x<em>во2степени</em>-8x-2x-8=-x<em>во2степени</em>+8-18x </span>
Tg(x+π/4)-2tgx=2
(tgx+tgπ/4)/(1-tgx*tgπ/4) -2tgx=2
(tgx+1)/(1-tgx)-2tgx=2
(tgx+1)/(1-tgx)-2(tgx+1)=0
(tgx+1)*(1-2+2tgx)/(1-tgx)=0
(tgx+1)(2tgx-1)=0,tgx≠1
tgx+1=0⇒tgx=-1⇒x=-π/4+πn не удов усл
2tgx-1=0⇒tgx=1/2
cos²x=1:(1+tg²x)=1:(1+1/4)=1:5/4=4/5
cosx=2/√5
sinx=√(1-cos²x)=√(1-4/5)=√(1/5)=1/√5
sin2x=2sinxcosx=2*1/√5*2/√5=4/5
sin2x = 2sinx*cosx ; cosx*tgx = sinx ; sin^2x*cos^2x=1