б) (2а-7у)-(5а-7у) = 2а-7у-5а+7у = -3а
в) 9х+3(15-8х) = 9х+45-24х = 45-15х
г) 33-8(11b-1)-2b = 33-88b+8-2b = 41-90b
√8x - 15x² - 1 = 0
- 15x² + 8x - 1 = 0²
15x² - 8x + 1 = 0
D = b² - 4ac = ( - 8)² - 4 × 15 × 1 = 64 - 60 = 4 = 2²
x₁ = 8 + 2 / 30 = 10 / 30 = 1/3
x₂ = 8 - 2 / 30 = 6 / 30 = 1 / 5
(-а)^2 = а^2
а^2 * а^3 = а^5
(2c-y)(2c+y)-(2c-y)=-(2c+y)
63^30 3^60*5^30
15^60+30=15^90
63^30 15^90
315^30 315^90