Question

na figura a seguir,pq//bc. determine o valor da medida de x

Answer 1

$\frac{12}{x} = \frac{5x+1}{4} \\ \\ x(5x+1)=4.(12) \\ \\ 5x^2+x=48 \\ \\ 5x^2+x-48=0$ 

equação do 2° grau

a=5
b=1
c=-48

Δ=b²-4ac
Δ=1²-4(5)(-48)
Δ=1+960
Δ=961

$x= \frac{-b\pm \sqrt{\Delta} }{2a} = \frac{~-1\pm \sqrt{961} }{2.(5)} = \frac{~-1\pm31}{10} \\ \\ x'= \frac{-1+31}{10} = \frac{30}{10} =3 \\ \\ x"= \frac{-1-31}{10} =- \frac{32}{10} =-3,2~~n/serve$ 

logo  x = 3