Question

X + y = 20
X * y = 5

Answer 1

x + y = 20 ---> x = 20 - y
x . y = 5

vamos substituir x = 20 - y

x . y = 5

( 20 - y ) . y = 5

20y - y^2 = 5

- y^2 + 20y - 5 = 0

a = - 1. b = 20. c = - 5

vamos encontrar a formula da delta

D = b^2 - 4 a c

D = (20)^2 - 4 (-1)(-5)

D = 400 + 4(-5)

D = 400 - 20

D = 380

vamos encontramos com a formula de braskara :

y = - b - , + \/ D
......._________
...............2a

y = - ( 20 ) - , + \/ 380
......______________
..................2 ( - 1 )

y = - 20 - , + 19,49
......____________
...............- 2

y1 = - 20 - 19,49
.......__________
................- 2

y1 = - 39,49
......._______
..............- 2

y1 = 39,49
......._____
............2

y1 = 19,745


y2 = - 20 + 19,49
........__________
..................- 2

y2 = - 0,51
........._____
.............- 2

y2 = 0,51
........____
....... ....2

y2 = 0,255