Question

1) resolva as seguintes proporções:
a)x = 21                d) 5x+3 = -21
  5    35                      10       30

b)10 = 50               e) 5  = 30
    7     x                  x+4   54

c)1 = x-6
   7   49

Answer 1

$a ) \frac{x }{5} = \frac{21}{35} \\ \\ 35x = 21.5 \\ 35x = 105 \\ \\ x= \frac{105}{35} \\ \\ \boxed{x = 3} \\ \\ b) \frac{10}{7} = \frac{50}{x} \\ \\ 10x = 50.7 \\ 10x = 350 \\ \\ x = \frac{350}{10} \\ {x = 35 }$


$c ) \frac{1}{7} = \frac{x-6}{49} \\ \\ 7(x-6) = 49 \\ 7x - 42 = 49 \\ 7x = 49 + 42 \\ 7x = 91 \\ x = \frac{91}{7} \\ \boxed{x =13}$

$d ) \frac{5x+3}{10} = \frac{-21}{30} \\ 30(5x+3) = -21 . 10 \\ 150x + 90 = -210 \\ 150x = -210 - 90 \\ 150x = -300 \\ \\ x = \frac{-300}{150} \\ \\ \boxed{x = -2}$

$e ) \frac{5}{x+4} = \frac{30}{54} \\ \\ 30(x+4) = 54.5 \\ 30x + 120 = 270 \\ 30x = 270 - 120 \\ 30x = 150 \\ \\ x = \frac{150}{30} \\ \\ \boxed{x = 5}$