Ta có: \(\dfrac{26-c}{45}=\dfrac{7}{15}\)

\(\Rightarrow390-15c=315\Rightarrow15c=75\Rightarrow c=5\)

GTLN nha bạn

\(\dfrac{3-\sqrt{x}}{\sqrt{x}-2}=-\left(\dfrac{\sqrt{x}-2}{\sqrt{x}-2}\right)-\dfrac{1}{\sqrt{x}-2}=-1-\dfrac{1}{\sqrt{x}-2}\le-1-\dfrac{1}{2}=-\dfrac{3}{2}\)\(ĐTXR\Leftrightarrow x=0\)

D. finish

\(\sqrt{\dfrac{2-\sqrt{3}}{2+\sqrt{3}}}+\sqrt{\dfrac{2+\sqrt{3}}{2-\sqrt{3}}}=\sqrt{\dfrac{\left(2-\sqrt{3}\right)^2}{4-3}}+\sqrt{\dfrac{\left(2+\sqrt{3}\right)^2}{4-3}}=2-\sqrt{3}+2+\sqrt{3}=4\)

a. 7, 10, 13,16, 19, 22, 25.

b. 103, 95, 87,79, 71, 63, 55, 47.

\(\widehat{B}=\)53⁰7'