Question

calcule as expressoes 2x(x+1)-x(x-5)=3(12-x)

Answer 1

2x (x + 1) - x (x - 5) = 3 (12 - x)
2x² + 2x - x² + 5x = 36 - 3x
2x² - x² + 2x + 5x + 3x - 36 = 0
x² + 10x - 36 = 0
a = 1, b = 10, c = - 36

Δ = b² - 4ac
Δ = 10² - 4 . 1 . (- 36)
Δ = 100 + 144
Δ = 244

x = (- b ± √Δ)/2a
x = (- 10 ± √244)/2 . 1
x = (- 10 ± √(2² . 61))/2
x = (- 10 ± 2√61)/2
x = - 5 ± √61

x = - 5 + √61
x = - 5 - √61