23.
1 - 2x+y = y-2x-y = -2
7x 7xy 7xy 7y
24.
(c⁻⁸)⁻⁶ = c⁴⁸⁻(⁻⁴) =c⁴⁸⁺⁴=c⁵²
c⁻⁴
27.
4a - 4 = 4a - 4 = 4a - 4(a-8b) = 4a-4a+32ab =
a²-64b² a+8b (a-8b)(a+8b) a+8b (a-8b)(a+8b) a² - 64b²
= 32ab
a² - 64b²
26.
(u+6v+9v²) : (1+ 3v) = (u² + 6vu+9v²) : (u+3v) = (u+3v)² * u = u+3v
u u u u u u+3v
12+3√2+3(-16-√2)=12+3√2-48-3√2=12-48=-36