x^2 = 48/3
x^2 = 16
x = ± √16
x = <span>± 4 </span>
1.5x = 75-2.5y | /1.5
x = (75-2.5y)/1.5
x = 75/1.5 - 2.5y/1.5
x = 50 - 2.5y/(2/3) -дробь
x = 50 - 2.5y×(3/2)
x = 50 - (5/2)y×(3/2) -(2 и 2 сокращаются)
x = 50 - 5y×(1/3)
x = 50 - (5/3)y
Как-то так.
1) 4x^2≤25
4x^2 - 25 ≤0
(2х-5)×(2х+5) ≤ 0
<span>у=log₂₀(x²-x)
</span>log₂₀(x²-x)>0
x²-x>1
x²-x-1 = (x-1/2+√5/2)(x-√5/2-1/2)>0
x∈(-∞, 1/2-√5/2)⋃(√5/2+1/2, ∞)
2xy=12
x² + y² = 13
Складывая и вычитая получаем новую систему
x² + 2xy + y² =25
x² - 2xy + y² = 1
x+y=5
x-y=1 x=3 y=2
или
x + y =5
x-y = -1 x=2 y=3
x+y =-5
x-y = 1 x=-2 y=-3
x+y = -5
x-y =-1 x=-3 y=-2