Question

resolva os sistemas {x²-y=10
{x+2y=5

Answer 1

x + 2 y = 5
x = 5 - 2 y

x² - y = 10
(5 - 2 y )² - y = 10
4 y² - 20 y + 25 - y  = 10
4 y² -21 y + 25 = 10
4 y² -  21 y + 25 - 10 = 0
4 y² - 21 y + 15 = 0
Δ = b² - 4 . a . c
Δ = -21² - 4 . 4 . 15
Δ = 441 - 240
Δ =201 \/¨¨201 =14,1
y = -b +ou- 14,1/2.4
y= 21 +ou- 14,1/8
y = 21 + 14,1/8
y´ = 35,1/8
y´= 4,3
y" = 21 - 14,1/8
y" = 6,9/8
y" = 0,86