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
(6 3/8 - 2 3/4) * (- 4) + 7/18 * 9 = - 11
1) 6 3/8 - 2 3/4 = 6 3/8 - 2 6/8 = 5 11/8 - 2 6/8 = 3 5/8
2) 3 5/8 * (- 4) = 29/8 * (- 4) = - 29/2 = - 14 1/2
3) 7/18 * 9 = 7/2 = 3 1/2
4) - 14 1/2 + 3 1/2 = - 11
к
У=___ формула обратной пропорц.
х
12=к/-3⇒к=-3*12⇒к=-36 у=-36/х
б)4=к/8 к=4*8 к=32 у=32/х
16х²у⁴ - 81х⁸ = х²(16у⁴ - 81х⁶) = х²((4у²)² - (9х³)²) =
= х²(4у² - 9х³)(4у² + 9х³)