Question

Nas figuras,calcule x, sabendo que a//b//c//

Answer 1

A)

4 / x  =  x + 7 / 7,5 
x (x + 7) = 4 * 7,5
x^2 + 7x = 30
x^2 + 7x - 30 = 0
Delta = 49 + 120
Delta  = 169

X = - b + raiz de delta / 2a
X = - 7 + 13 / 2
X = 6 / 2 
X = 3

B)

10/ 4 = 15 / X^2 + 5
10 * (X^2 + 5) = 60
10X^2 + 50 - 60 = 0   (simplificando por dois)
5x - 5 = 0
Delta = 0 - 4 * 5 * (-5)
Delta =  100

X = - b + raiz de delta / 2a
X = 0 + 10 / 10
X = 1