\begin{cases}a-7=\dfrac{b}{a}\\b+4=\dfrac{b}{a}\end{cases} Giúp em với ;( 22/08/2021 Bởi Raelynn \begin{cases}a-7=\dfrac{b}{a}\\b+4=\dfrac{b}{a}\end{cases} Giúp em với ;(
\begin{cases}a-7=b/a\\b+4=b/a\\\end{cases} `⇒a-7=b+4` `⇒a-b=11` `⇒a-11=b` `a-7=b/a` `⇔a^2-7a=b` `⇒a^2-7a=a-11` `⇒a^2-8a+16=5` `⇒(a-4)^2=5` `⇒`\(\left[ \begin{array}{l}a=\sqrt [2]5 +4\\a=4-\sqrt [2]5\end{array} \right.\) `⇒`\(\left[ \begin{array}{l}b=\sqrt[2]5-7\\b=-\sqrt[2]5-7\end{array} \right.\) Bình luận
\begin{cases}a-7=b/a\\b+4=b/a\\\end{cases}
`⇒a-7=b+4`
`⇒a-b=11`
`⇒a-11=b`
`a-7=b/a`
`⇔a^2-7a=b`
`⇒a^2-7a=a-11`
`⇒a^2-8a+16=5`
`⇒(a-4)^2=5`
`⇒`\(\left[ \begin{array}{l}a=\sqrt [2]5 +4\\a=4-\sqrt [2]5\end{array} \right.\)
`⇒`\(\left[ \begin{array}{l}b=\sqrt[2]5-7\\b=-\sqrt[2]5-7\end{array} \right.\)