1)5х^3-20х^2=02)9x-x^3=03)x^3+3x^2-4x-12=04)x^3-2x^2=05)9x^2-0.25=06)64-9x^2=07)2x^3-x^2-18x+9=08)x^2-6x+9=09)x^2+10x+25=010)4x^2-4x+1=011)9x^2+6x+1=012)3x-0.4x^2=013)-0.4x^2+8x=0

1) [latex]5x^3-20x^2=0[/latex] [latex]5x^2(x - 4) = 0[/latex] 5x² = 0 или x-4=0 x = 0 или x=4 2) 9x - x³ = 0 x(9 - x²) = 0 x= 0 или 9 - x² = 0 x = 0 или x² = 9 ⇒ x= -3 или x= 3 Ответ: -3, 0, 3 3) x³ + 3x² - 4x - 12 = 0  (x³ + 3x²) - (4x + 12) = 0 x²(x + 3) - 4(x + 3) = 0 (x² - 4)(x + 3) = 0 x² - 4 = 0 или x+3 = 0 x=2 или x=-2 или x=-3 4) x³ - 2x² = 0  x^2(x - 2) = 0 x = 0 или x=2 5) 9x² - 0.25 = 0 9x² = 0.25 x² = 1/36 x = 1/6 или x=-1/6 6) 64 - 9x² = 0 9x² = 64 x² = 64/9 x = 8/3 или x= - 8/3 7) 2x³ - x² - 18x + 9 = 0 (2x³ - x²) - (18x - 9) = 0 x²(2x - 1) - 9(2x - 1) = 0 (x² - 9)(2x - 1) = 0 x²=9 или 2x - 1 = 0 x = -3 или x= 3 или x = 1/2 8) x² - 6x + 9 = 0 (x - 3)² = 0 x - 3 = 0 x = 3 9) x²+10x+25=0 (x + 5)² = 0 x + 5 = 0 x = -5 10) 4x² - 4x + 1 = 0 (2x - 1)² = 0 2x - 1 = 0 2x = 1 x = 1/2 11) 9x²+6x+1=0 (3x + 1)² = 0 3x +1 = 0 x = -1/3 12) 3x - 0.4x²=0 x(3 - 0.4x) = 0 x = 0 или 3-0.4x = 0 ⇒ (2/5)x = 3 ⇒ x = 15/2 = 7.5 13) -0.4x² + 8x = 0 x( 8 - 0.4x) = 0 x = 0 или 0,4x = 8 ⇒ x = 20