Question

Answer 1

Bài 3: \(\dfrac{a^2+c^2}{b^2+c^2}=\dfrac{a^2+ab}{b^2+ab}=\dfrac{a\left(a+b\right)}{b\left(a+b\right)}=\dfrac{a}{b}\)

Bài 4: \(\dfrac{3a^2-b^2}{a^2+b^2}=\dfrac{3}{4}\Leftrightarrow3a^2+3b^2=12a^2-4b^2\Leftrightarrow9a^2=7b^2\Leftrightarrow\dfrac{9a^2}{7b^2}=1\Leftrightarrow\dfrac{a^2}{b^2}=\dfrac{7}{9}\Leftrightarrow\left[{}\begin{matrix}\dfrac{a}{b}=\dfrac{7}{9}\\\dfrac{a}{b}=-\dfrac{7}{9}\end{matrix}\right.\)

Answer 2

Bài 2:

\(8^7-2^{18}=2^{21}-2^{18}=2^{18}\cdot7=2^{17}\cdot14⋮14\)

Answer 3

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