\(m = 40280,45\) và\(n = 402,8049\)

\(=>m>n\)

\(\dfrac{\left(1,15-x\right)5,25}{\dfrac{36}{17}\left(\dfrac{95}{9}-\dfrac{29}{4}\right)}=\dfrac{3}{4}< =>\dfrac{6,0375-5,25x}{7}=\dfrac{3}{4}\)

\(\Rightarrow6,0375-5,25x=5,25=>x=0,15\)

Bai 1

Cạnh hình thoi dài số xm là 

28:4=7(dm) 

đổi 7dm=70cm 

AB =\(\sqrt{BC^{^2}-AC^{^2}}=\sqrt{15^{^2}-12^{^2}}=9\)(CM)

AH=\(\dfrac{AC.AB}{BC}=7.2\)(CM)

CH=\(\dfrac{AC^{^2}}{BC}=\dfrac{12^{^2}}{15}=9,6\left(CM\right)\)

A1=B3

A2=B2

B3+B4=180 độ (vì B3+B3=180 độ MÀ B2=B3đối đỉnh  )

B4=A2( đối đỉnh)

Bài 3 

B=(\(\dfrac{3}{\sqrt{1+a}}+\sqrt{1-a}\))\(\left(\dfrac{\sqrt{1-a}\sqrt{1+a}}{3+\sqrt{1-a^{^2}}}\right)\)

=\(\left(\dfrac{3+\sqrt{1-a^{^2}}}{\sqrt{1-a}}\right)\left(\dfrac{\sqrt{1-a}\sqrt{1+a}}{3+\sqrt{1-a^{^2}}}\right)=\sqrt{1+a}\)

b) a=\(\dfrac{\sqrt{3}}{2+\sqrt{3}}=>B=\sqrt{1+\dfrac{\sqrt{3}}{2+\sqrt{3}}}=>\)B=1,21

UCLN(120,180)=60

UCLN(54,90,126)=18

\((3x-2)+(x+1)=3 =>4x=4=>x=1\)