3x²-5x=0 x^2-5x-24 = 0

7x^2-22x+3=0

7x^2-6x+2=0

4x^2+12x+9=0

1) 3x^2 - 5x = 0

x (3x - 5) = 0

x = 0 3x=5

x = 5/3

корни 0 и 5/3

2) x^2 - 5x - 24 = 0

x1 + x2 = 5

x1 * x2 = - 24 (теорема Виета)

x1 = 8 x2 = - 3

3) 7x^2 - 22x + 3 = 0

D = 484-84 = 400 = 20^2

x1 = 3

x2 = 1/7

4) 7x^2 - 6x + 2 = 0

D = 36-56 < 0

D<0 корней нету

5) 4x^2 + 12x + 9 = 0

D = 144-144 = 0

D = 0 только один корень

x = - 12/8 = - 3/2 = - 1.5