Question

resolva a equação (x+5). (x-3)-x=5​

Answer 1

Resposta:

x²-3x+5x-15 - x = 5

x²+ 2x -15 -x = 5 

x² + x -15=5 

x² + x -15 - 5 = 0 

x²+ x -20= 0 

pronto

Resolvendo por Bháskara: 

Δ = b²−4ac

Δ = 1²−4⋅1⋅(−20)

Δ = 1 + 80

Δ = 81

x = -b ± √Δ / 2.a

x = -1 ± √81 / 2.1

x = -1 ± 9 / 2

x = -1 - 9 / 2

x' = -10 / 2

x' = -5

x'' = -1 + 9 / 2

x'' = 8 / 2

x'' = 4

S = {-5, 4}

Answer 2

Oie, Td Bom?!

$(x + 5) \: . \: (x - 3) - x = 5$

$x {}^{2} - 3x + 5x - 15 - x = 5$

$x {}^{2} + x - 15 = 5$

$x {}^{2} + x - 15 - 5 = 0$

$x {}^{2} +x - 20 = 0$

• Coeficientes:

$a = 1 \: ,\: b = 1 \: , \: c = - 20$

• Fórmula resolutiva:

$x = \frac{ - b± \sqrt{b {}^{2} - 4ac } }{2a}$

$x = \frac{ - 1± \sqrt{1 {}^{2} - 4 \: . \: 1 \: . \: ( - 20)} }{2 \: . \: 1}$

$x = \frac{ - 1± \sqrt{1 + 80} }{2}$

$x = \frac{ - 1± \sqrt{81} }{2}$

$x = \frac{ - 1±9}{2}$

$⇒x = \frac{ - 1 + 9}{2} = \frac{8}{2} = 4$

$⇒x = \frac{ - 1 - 9}{2} = \frac{ - 10}{2} = - 5$

$S = \left \{ - 5 \: , \: 4 \right \}$

Att. Makaveli1996