Question

qual deve ser o capital aplicado a uma taxa de juro simples de 25% a.a para que em 6 meses renda R$425.00 de juro?

Answer 1

taxa (i) = 25% a.a. = 0,25
tempo (t) = 6 meses = 0,5 a
juros (j) = 425,00
capital (c) = ...

j = cit
cit = j
c = j/it
c = 425/0,25*0,5
c = 425/0,125
c = 425000/125
c = 17000/5
c = 3400
O capital será de R$ 3.400,00

Answer 2

$\sf\large \boxed{\boxed{\tt J = C \cdot i \cdot t}}$

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$\sf \displaystyle 425\:=\:C\:\cdot 0,\:25\:\cdot \left(\frac{1}{2}\right)\\\\\\\sf \boxed{\star \sf \ {Troque \:os \:lados} }\\\\\\\sf C\cdot \:0.25\left(\frac{1}{2}\right)=425\\\\\\\sf C\frac{0.25}{2}=425\\\\\\\sf 2C\frac{0.25}{2}=425\cdot \:2\\\\\\\sf 0.25C=850\\\\\\\sf \frac{0.25C}{0.25}=\frac{850}{0.25}\\\\\\\\\large \to \boxeed{\boxed{\sf C=3400}}$