Verified answer

A)

9/x=x/4

x²=36

x=6

B)

(x+6)/(x=x/(x-3)

x²=x²+3x-18

3x-18=0

3x=18

x=18/3

x=6

a)

an=a1.r(elevado a n-1)

9=4.(x/4)²

9=4(x²/4)

9=4x²/16

9.16=4x²

x²=144/4

x=6

b)

an=a1.r(elevado a n-1)

x+6=x-3.(x/x-3)²

x+6=x-3.x²/x-3

x+6=x³-3x²/x²-6x+9

x+6.(x²-6x+9)=x³-3x²

x³-6x²+9x+6x²-36x+54=x³-3x²

x³-x³+6x²-6x²=-9x+36x-3x²

0=3x²+27x

3x²+27x=0 (baskara)

x'=0 x''=9

x=9