<span>5(21- 2x) = 25(x) </span>
<span>5^(21-2x) = 25^(x)</span>
5^(21-2x) = 5^(2x)
21 - 2x = 2x
4x=21
x=5.25
5sinx + 12cosx
r = √(a^2 + b^2) = √(5^2 + 12^2) = 13
cost = 5/13
sint = 12/13
t= arcsin 12/13
5/13*sinx + 12/13*cosx = 13*(5/13sinx + 12/13cosx) =
= 13 sin (x + arcsin 12/13)
10x^2+16x-512+5x^2+80x+320=15x^2+96x-192=3(5x^2+32x-64)
100-19=81
3570/81=44
44*100=4400
Ответ: 4400 рублей
2,5a(a-2y)-2y(y-2.5a)=
2,5а²-5ау-2у²+5ау=
2,5а²-2у²=
2,5 × (-0,2)² - 2 × (-0,5)²=
2,5 × 0,04 - 2×0,25=
0,1 - 0,5=-0,4