\(\frac{138\cdot138-690}{137\cdot137-548}\)=\(\frac{137+1\cdot137+1-548+142}{137\cdot137-548}\)=\(\frac{1+1+142}{1}\)=\(\frac{144}{1}\)=144

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A=\(\dfrac{5.11.13.\left(1-2\right)}{22.26.\left(1-2\right)}=\dfrac{5.11.13}{2.2.11.13}=\dfrac{5}{4}\)

B=\(\dfrac{138.\left(138-5\right)}{137\left(137-4\right)}=\dfrac{138.133}{137.133}\dfrac{138}{137}\)

Ta có : 

\(A=\frac{5\left(11.13-22.26\right)}{22.26-44.52}=\frac{5\left(11.13-22.26\right)}{4\left(11.13-22.26\right)}=\frac{5}{4}\)

\(B=\frac{138^2-690}{137^2-548}=\frac{138\left(138-5\right)}{137\left(137-4\right)}=\frac{138.133}{137.133}=\frac{138}{137}\)

Lại có : 

\(1-\frac{5}{4}=-\frac{1}{4}\)

\(1-\frac{138}{137}=-\frac{1}{137}\)

Vì \(\frac{-1}{4}< \frac{-1}{137}\) nên \(\frac{5}{4}>\frac{138}{137}\) \(\Rightarrow\) \(A< B\)

Vậy \(A< B\)

Ta có :\(A=\frac{5\left(11.13-22.26\right)}{22.26-44.52}=\frac{5\left(11.13-22.26\right)}{2\left(11.13-22.26\right)}=\frac{5}{2}\)

\(B=\frac{138^2-138.5}{137^2-137.4}=\frac{138\left(138-5\right)}{137\left(137-4\right)}=\frac{138}{137}\)

Ta thấy A>B

làm thế nào cho nó gọn gọn xíu rồi ss nha

\(A=\dfrac{5\left(11.13-22.26\right)}{22.26-44.52}\)
\(=\dfrac{5\left(11.13-22.26\right)}{2\left(11.13-22.26\right)}\)
\(=\dfrac{5}{2}\)
\(B=\dfrac{138^2-690}{137^2-548}\)
\(=\dfrac{138^2-138.5}{137^2-137.4}\)
\(=\dfrac{138\left(138-5\right)}{137\left(137-4\right)}\)
\(=\dfrac{138.133}{137.133}\)
\(=\dfrac{138}{137}\)
Ta có:
\(\dfrac{5}{2}=\dfrac{685}{274}\)
\(\dfrac{138}{137}=\dfrac{276}{274}\)
Vì vậy mà \(A>B\)
#die

A-B=-x thi A<B.    Voi x>0

 Lam trac nghiem kieu nay la dc day. Hi

cậu có thể làm rõ hơn kkhông