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2x^2-6x+4<=0 x^2-3x+2<=0 (x-1)(x-2)<=0 x принадлежит [1;2] ..........................................................................................................................................................................................................
(x-5)²-x(x+3)=12
(x-5)(x-5)-x(x+3)=12
x²-10x+25-x²-3x=12
-13x=12-25
-13x=-13
x=1
(3.6)²-(2.6)²=(3.6-2.6)(3.6+2.6)=1*6.2=6.2
2 / x - 5 = 3x / x + 3
2( x + 3) = 3x ( x - 5)
2x + 6 = 3x² - 15x
2x + 6 - 3x² + 15x = 0
- 3x² + 17x + 6 =0
3x² - 17x - 6 = 0
D = b² - 4ac = ( - 17)² - 4 × 3 × ( - 6) = 289 + 72 = 361 = 19²
x₁ = 17 + 19 / 6 = 6
x₂ = 17 - 19 / 6 = - 2 / 6 = - 1/3