<span>2x=18-3y 2*(18-3y)-5y=-19 36-6y-5y=-19 11y=55 y=5 2x=18-15 x=3/2</span>
Раскройте скобки: (sinx)^2+2sinx cosx+(cosx)^2=1+sin(2x)=1+3/5=1+0.6=1.6
Объяснение:
-(2а-3)²-5(3а-7)(4+а)-3а²-2=
-(4а²-12а+9)-5(12а-28+3а²-7а)-3а²-2=-4а²+12а-9-5(5а-28+3а)-3а²-2=
-4а²+12а-9-25а+140-15а-3а²-2=
=-7а²-28а+129
sqrt(1+1/a^2+1/(a+1)^2) = sqrt((a^4+2a^3+3a^2+2a+1)/(a^2*(a+1)^2)) = sqrt((a^2+a+1)^2/(a^2*(a+1)^2)) = (a^2+a+1)/(a(a+1)) = 1+(1/(a(a+1)) 1+ 1/a-1/(a+1)
Значит
sqrt(1 + 1/1^2 + 1/2^2) + sqrt(1 + 1/2^2+1/3^2 ) + ... + sqrt(1 + 1/99^2 + 1/100^2 ) = 99 + (1/1+1/2+...+1/99) - (1/2+1/3+...+1/100) = 99+1-1/100 = 999/100
√60+(√3 - √5)²=√(4*15)+(√3)² - 2√(3*5)+(√5)²=2√15+3-2√15+5=8