1) x² + 2 - 3 + x = 0
x² + x - 1 = 0
D = b² - 4ac = 1 - 4×(-1) = 5
x1,2 = ( - 1 + √5) / 2
2) 5x + 2 - 2 + 2x² = 0
2x² + 5x = 0
x( 2x + 5) = 0
x =0
2x + 5 = 0
2x =- 5
x =- 2,5
3) 2x² + 3 - 3 + 7x = 0
2x² + 7x = 0
x( 2x + 7) = 0
x = 0
2x+ 7 = 0
2x = - 7
x = - 3,5
4) x² - 6x - 4x + 25 = 0
x² - 10x + 25 = 0
D = b² - 4ac = 100 - 4×25 = 0 - имеет один корень.
x= - b/2a
x = 10/2
x = 5
5) x² + 2x - 16x + 49 = 0
x² - 14x + 49 = 0
D = b² - 4ac = 196 - 4×49 = 0 - имеет один корень.
x =- b/2a
x = 14/2
x = 7