Respostas

2014-02-25T16:48:46-03:00
(x-1)(2x+5)=60
2x²+5x-2x-5-60=0
2x²+3x-65=0

resolvendo baskara:
Δ=b²-4ac
Δ= 3² - 4.2.-65
Δ=9+520
Δ=529

-b+-√Δ / 2a
-3+-√529 /2.2
-3+-23 /4
x¹ = 20/4=5
x²=-26/4 ignora o valor negativo..

x=5

testando:
x-1 = 5-1 =4
2x+5 = 2x5+5 = 15

a=b*h = 4*15 = 60cm²

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