A) -(a+b)(a+b)=-(a²+2ab+b²)=-a²-2ab-b²
в) -(x-y)(x-y)=-(x²-2xy+y²)=-x²+2xy-y²
д) -(5a-2b)(3b+2a)=-(15ab+10a²-6b²-4ab)=-10a²+6b²-11ab
15/(a - b) · (b - a)/10 = 15(b - a)/(a - b)10 = 3(-a + b)/(a - b)2 = (-3)(a - b)/(a - b)2 = (-3)/ /2 = (-1,5)
(-a - b/a)² = a² - (a · 2 · b/a) + (b/a)² = a²/1 - (2ab/a) + (b²/a²) = a⁴/a² - 2ba²/a² + b²/ /a² = (a⁴ - 2a²b + b²)/a²
3/(a - b)² ÷ (-3)/(a - b) = 3/(a - b)(a - b) · (a - b)/(-3) = 3(a - b)/(a - b)(a - b)(-3) = 1/(-1)(a -- b) =1/((-a) + b) = 1/(b - a)
1/(a + b) ÷ 1/3x(a + b) = 1/(a + b) · 3x(a + b)/1 = 3x(a + b)/(a + b) = 3x
(2/b)² · (b/4)² = 2²/b² · b²/4² = 4/b² · b²/16 = 4b²/16b² = 1/4
(9 - y²)/(3 - y) · y/(y² + 6y + 9) = (3 - y)(3 + y)/(3 - y) · y/(y + 3)² = y(3 - y)(y + 3)/(3 - y)(y + 3)(y + 3) = y/(y + 3)
(x² + 5x)/(x² - 4) ÷ (x² + 10 + 25)/(x + 2) · (x + 5)/x = x(x + 5)/(x - 2)(x + 2) ÷ (x + 5)²/
/(x + 2) · (x + 5)/x = x(x + 5)/(x - 2)(x + 2) · (x + 2)/(x + 5)(x + 5) · (x + 5)/x = x(x + 5)(x + + 2)(x + 5)/(x - 2)(x + 2)(x + 5)(x + 5)x = 1/(x - 2)
(1 - (x/y)²) ÷ (1/x - 1/y) = (1 - (x²/y²)) ÷ (y/xy - x/xy) = (y²/y² - x²/y²) ÷ (y - x)/xy = (y² - x²)/ /y² · xy/(x - y) = (y - x)xy²/y²(x - y) = (-(x - y))xy²/y²(x - y) = (-x)
Ctg(270-4a)=tg4a=2tg2a/(1-tg²2a)=2*4/3:(1-16/9)=8/3:(-7/9)=-8/7
cosa=√1-1/5=2/√5
sin2a=2sinacosa=2*1/√5*2/√5=4/5
cos2a=√1-16/25=3/5
tg2a=sin2a/cos2a=4/5:3/5=4/2*5/3=4/3
100-90=10\% - процентное содержание сухого вещества в свежих грибах
44:10=4.4 кг - масса сухого вещества
5-4.4=0.6 кг - масса воды в сушеных грибах
5 кг - 100\%
0.6 кг - х\%
х=100*0.6:5=12\%
ответ - 12\% воды в сушеных грибах
