3,4-0,8=2,6-скорость течения
3,4+2,6=6 ск лодки по теч
![...=\dfrac{(3^2-2^2)(3^2+2^2)(3^4+2^4)(3^8+2^8)(3^{16}+2^{16})}{3^2-2^2}=\\ \\ \\ =\dfrac{(3^4-2^4)(3^4+2^4)(3^8+2^8)(3^{16}+2^{16})}{9-4}=\dfrac{(3^8-2^8)(3^8+2^8)(3^{16}+2^{16})}{5}=\\ \\ \\ =\dfrac{(3^{16}-2^{16})(3^{16}+2^{16})}{5}=\dfrac{3^{32}-2^{32}}{5}=0.2(3^{32}-2^{32})](https://tex.z-dn.net/?f=...%3D%5Cdfrac%7B%283%5E2-2%5E2%29%283%5E2%2B2%5E2%29%283%5E4%2B2%5E4%29%283%5E8%2B2%5E8%29%283%5E%7B16%7D%2B2%5E%7B16%7D%29%7D%7B3%5E2-2%5E2%7D%3D%5C%5C%20%5C%5C%20%5C%5C%20%3D%5Cdfrac%7B%283%5E4-2%5E4%29%283%5E4%2B2%5E4%29%283%5E8%2B2%5E8%29%283%5E%7B16%7D%2B2%5E%7B16%7D%29%7D%7B9-4%7D%3D%5Cdfrac%7B%283%5E8-2%5E8%29%283%5E8%2B2%5E8%29%283%5E%7B16%7D%2B2%5E%7B16%7D%29%7D%7B5%7D%3D%5C%5C%20%5C%5C%20%5C%5C%20%3D%5Cdfrac%7B%283%5E%7B16%7D-2%5E%7B16%7D%29%283%5E%7B16%7D%2B2%5E%7B16%7D%29%7D%7B5%7D%3D%5Cdfrac%7B3%5E%7B32%7D-2%5E%7B32%7D%7D%7B5%7D%3D0.2%283%5E%7B32%7D-2%5E%7B32%7D%29)
Каждый раз применяли формулу разность квадратов.
540/8x=30
30*8x=540
240x=540
x=540/240
x=54/24
x=2.25
800:100=8 человек- один процент всех учеников
8*14=112 имеют годовую оценку 12 баллов
Вот, ничего сложного^^