Câu hỏi của Thẩm Thiên Tình

Question

Rút gọn

$A=\sqrt{63}-2\sqrt{175}+\sqrt{252}-\dfrac{1}{7}\sqrt{28}$

Như Khương Nguyễn · Accepted Answer

$A=...$

$=3\sqrt{7}-2.5\sqrt{7}+6\sqrt{7}-\dfrac{1}{7}.2\sqrt{7}$

$=\left(3-2.5+6-\dfrac{1}{7}.2\right)\sqrt{7}$
$=-\dfrac{9\sqrt{7}}{7}$Câu trả lời: $A=...$

$=3\sqrt{7}-2.5\sqrt{7}+6\sqrt{7}-\dfrac{1}{7}.2\sqrt{7}$

$=\left(3-2.5+6-\dfrac{1}{7}.2\right)\sqrt{7}$
$=-\dfrac{9\sqrt{7}}{7}$