<span> √x^15 y^2 = х^7 * у * √х</span>
2cos^2x-2sin2x+1=0.
2cos^2x - 4sinxcosx + 1 = 0
2cos^2x - 4sinxcosx + sin^2x + cos^2x = 0
sin^2x - 4sinxcosx + 3cos^2x = 0 /: cos^2x не рав. 0
tg^2x - 4tgx +3=0
(tgx - 1 )(tgx - 3 ) = 0
1) tgx = 1 ==> x = pi/4 +pik, k c Z
2) tgx = 3 ===> x = arctg(3) +pik, k c Z
Подробнее - на Znanija.com - znanija.com/task/3818797#readmore
0.6x * 3 + 0.4x * 2 + 3x = 1.8x + 1.7x + 6x = 9.5x=9.5 * (-2)= 19
Четыре целых одна шестая.