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Cho [tex]\frac{a}{b}=\frac{c}{d}[/tex] ( b,d khác 0) Chứng minh :
a. [tex]\frac{5a+3b}{5a-3b}=\frac{5c+3d}{5c-3d}[/tex]
b. [tex]\frac{a^2+b^2}{b^2+d^2}[/tex]=[tex]\frac{a^2+c^2}{b^2+d^2}=\frac{ac}{bd}[/tex]
c[tex]\frac{7a^2+3ab}{11a^2+8b^2}=\frac{7c^+3cd}{11c^2-8d^2}[/tex]
a. [tex]\frac{5a+3b}{5a-3b}=\frac{5c+3d}{5c-3d}[/tex]
b. [tex]\frac{a^2+b^2}{b^2+d^2}[/tex]=[tex]\frac{a^2+c^2}{b^2+d^2}=\frac{ac}{bd}[/tex]
c[tex]\frac{7a^2+3ab}{11a^2+8b^2}=\frac{7c^+3cd}{11c^2-8d^2}[/tex]