R=D/2
D=C/π
R²=S/π
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4c^2-8c-(c^2-8c+16)=
4c^2-8c-c^2+8c-16=
3c^2-16
(3x - 5)² = 9x²
9x² - 30x + 25 - 9x² = 0
- 30x = - 25
(2x + 3)² = 4x(2x + 3)
(2x + 3)² - 4x(2x + 3) = 0
(2x + 3)(2x + 3 - 4x) = 0
(2x + 3)(- 2x + 3) = 0
или 2x + 3 = 0 или - 2x + 3 = 0
2x = - 3 - 2x = - 3
x₁ = - 1,5 x₂ = 1,5
(5x - 7)² = (5(x + 1))²
(5x - 7)² = 25(x + 1)²
25x² - 70x + 49 = 25x² + 50x +25
25x² - 70x - 25x² - 50x = 25 - 49
- 120x = - 24
x = 0,2