Question

(X+4).(X-2)=5x+5 responda

Answer 1

(x + 4) . (x - 2) = 5x + 5

Use a propriedade distributiva (chuveirinho)

x.x - 2.x + 4.x - 4. 2 = 5x  + 5
x² - 2x + 4x - 8 = 5x  + 5
x² + 2x - 8 = 5x + 5
x² + 2x - 5x - 8 - 5 = 0
=> x² - 3x - 13 = 0

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Δ = b²−4ac
Δ = (−3)² −4⋅1⋅−13
Δ = 9 + 52
Δ = 61

x = -b ± √Δ / 2.a
x = -(-3 ± √61 / 2.1
x = 3 ± √61 / 2

x' = 3 -  √61 / 2

x'' = 3 + √61 / 2


S = (3 -  √61 / 2, 3 +  √61 / 2 )

Answer 2

(x+4).(x-2) = 5x + 5
x² - 2x + 4x -8= 5x - 5
x² + 2x - 5x - 8 + 5 = 0
x² - 3x - 3 = 0
 A(delta)                                 x = 
A = -(-3)² - 4. 1. (-3)
A = 21