Question

15 Pontos
Calcule o valor de x nas proporções:
a) 6/x = 9/12
b) 2x/3= -24/15
c) 3/4= 5x/20
d)x+3/4= 12/6

Answer 1

Oi,

basta multiplicar cruzado e efetuar as operações>

$\dfrac{6}{x}= \dfrac{9}{12}\\\\ 6\cdot12=9\cdot x\\ 72=9x\\ x=72/9\\ x=8$

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$\dfrac{2x}{3}=- \dfrac{24}{15}\\\\ 2x\cdot15=3\cdot(-24)\\ 15x=-72\\\\ x= -\dfrac{72}{15}= \dfrac{72\div3}{15\div3}= -\dfrac{24}{5} \\\\\\ x=- \dfrac{24}{5}$

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$\dfrac{3}{4}= \dfrac{5x}{20}\\\\ 3\cdot20=4\cdot5x\\ 60=20x\\\\ x= \dfrac{60}{20}\\\\ x=3$

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$\dfrac{x+3}{4}= \dfrac{12}{6}\\\\ \dfrac{x+3}{4}=2\\\\ x+3=4\cdot2\\ x+3=8\\ x=8-3\\ x=5$

Tenha ótimos estudos, e espero ter ajudado^^