Giúp với !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! $\sqrt[]{9x+18}$ $+$ $5\sqrt{x+2}$ $-$ $\frac{4}{5}$ $\sqrt{25x+50}$ $=$ $8$ $\\$
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$#Ben347$
Đáp án: $⇔x+$ $=$ $2$
Giải thích các bước giải:
$\sqrt[]{9x+18}$ $+$ $5\sqrt{x+2}$ $-$ $\frac{4}{5}$ $\sqrt{25x+50}$ $=$ $8$
$⇔\sqrt[]{(9x+2)}$ $+$ $5\sqrt{x+2}$ $-$ $\frac{4}{5}$ $\sqrt{25(x+2)}$ $=$ $8$
$⇔3\sqrt{x+2}$ $+$ $5\sqrt{x+2}$ $-$ $\frac{4}{5}$ $.5\sqrt{x+2}$ $=$ $8$
$⇔3\sqrt{x+2}$ $+$ $5\sqrt{x+2}$ $-$ $4\sqrt{x+2}$ $=$ $8$
$⇔4\sqrt{x+2}$ $=$ $8$
$⇔\sqrt{x+2}$ $=$ $2$
$⇔x+2$ $=$ $4$
$⇔x+$ $=$ $2$
${\sqrt[]{9x+18}+5\sqrt[]{x+2}-\dfrac{4}{5}\sqrt[]{25x+50}=8}$ ${ĐKXĐ:x≥-2}$
${⇔\sqrt[]{9(x+2)}+5\sqrt[]{x+2}-\dfrac{4}{5}\sqrt[]{25(x+2)}=8}$
${⇔3\sqrt[]{x+2}+5\sqrt[]{x+2}-4\sqrt[]{x+2}=8}$
${⇔4\sqrt[]{x+2}=8}$
${⇔\sqrt[]{x+2}=2}$
${⇔x+2=4}$
${⇔x=2,tm}$
Vậy ${x=2}$
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