(a+4b)^2-(4b-3a)*(4b+3a)+a(3b-5a)=a²+8b+16b²-(16b²-9a²)+3ab-5a²=a²+8ab+16b²-16b²+9a²+3ab-5a²=5a<span>²+11ab=a(5a+11b)</span>
S=70t
S(2,4)=70×2,4=168
S(3,8)=70×3,8=266
Log4(2-x)=log4(25)/log4(16)
log4(2-x)=log4(25)/2
log4(2-x)=1/2log4(25)
log4(2-x)=log4(25)^1/2
log4(2-x)=log4(5)
2-x=5
x=-3
Ответ: -3.
x⁴ = (x - 30)²
x⁴ - (x - 30)² = 0
(x²)² - (x - 30)² = 0
(x² - x + 30)(x² + x - 30) = 0
1) x² - x + 30 = 0
D = (-1)² - 4 * 30 = 1 - 120 = - 119 < 0 - корней нет
2) x² + x - 30 = 0
x₁ = 5 x₂ = - 6
Ответ : - 6 ; 5