Toán Lớp 7: Tìm a, b, c:
$\frac{1}{2}$a = $\frac{2}{3}$b = $\frac{3}{4}$c và a – b = 15
Leave a reply
Register Now
Login
Lost Password
Lost your password? Please enter your email address. You will receive a link and will create a new password via email.
Toán Lớp 7: Tìm a, b, c:
$\frac{1}{2}$a = $\frac{2}{3}$b = $\frac{3}{4}$c và a – b = 15
Comments ( 1 )
\dfrac{1}{2}a = \dfrac{2}{3}.b = \dfrac{3}{4}.c\\
\Leftrightarrow \dfrac{a}{{2.6}} = \dfrac{{2.b}}{{3.6}} = \dfrac{{3.c}}{{4.6}}\\
\Leftrightarrow \dfrac{a}{{12}} = \dfrac{b}{9} = \dfrac{c}{8} = \dfrac{{a – b}}{{12 – 9}} = \dfrac{{15}}{3} = 5\\
\Leftrightarrow \left\{ \begin{array}{l}
a = 5.12 = 60\\
b = 5.9 = 45\\
c = 5.8 = 40
\end{array} \right.\\
Vậy\,a = 60;b = 45;c = 40
\end{array}$