Question

a soma de um número ​

Answer 1

Resposta:

1) (9, -10); 2) (3, -4); 3) (1, 1); 4) (10, -8).

Explicação passo a passo:

1) x + x² = 90

x² + x - 90 = 0

x = - 1 ± √1² - 4 . 1 . (-90)/2 . 1

x = - 1 ± √1 + 360/2      

x = - 1 ± √361/2

x = - 1 ± 19/2

x' = - 1 + 19/2

x' = 18/2

x' = 9.

x" = - 1 - 19/2

x" = -20/2

x" = - 10.          

2) x² + x = 12

x² + x - 12 = 0

x = -1 ± √1² - 4 . 1 . (-12)/2 . 1

x = - 1 ± √1 + 48/2

x = - 1 ± √49/2

x = - 1 ± 7/2

x' = - 1 + 7/2

x' - 6/2

x' = 3.

x" = - 1 - 7/2

x" = - 8/2

x" = - 4.

3) x² - 2x = - 1

x² - 2x + 1 = 0

x = - (-2) ± √(-2)² - 4 . 1 . 1/2 . 1

x = 2 ± √4 - 4/2

x = 2 ± √0/2

x = 2 ± 0/2

x' = 2 + 0/2

x' = 2/2

x = 1.

x" = 2 - 0/2

x" = 2/2

x" = 1.

4) x² - 2x = 80

x² - 2x - 80 = 0

x = - (-2) ± √(-2)² - 4 . 1 . (-80)/2 . 1

x = 2 ± √4 + 320/2

x = 2 ± √324/2

x = 2 ± 18/2

x' = 2 + 18/2

x' = 20/2

x' = 10.

x" = 2 - 18/2

x" = - 16/2

x" = - 8.