A= 355+135/48-35.13 B= 683-523/16+68.52
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![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
a: Sửa đề: \(A=\dfrac{35^3+13^3}{48}-35\cdot13\)
\(=\dfrac{\left(35+13\right)\left(35^2-35\cdot13+13^2\right)}{48}-35\cdot13\)
\(=35^2-2\cdot35\cdot13+13^2=22^2\)
b: \(B=\dfrac{\left(68-52\right)\left(68^2+68\cdot52+52^2\right)}{16}+68\cdot52\)
\(=68^2+2\cdot68\cdot52+52^2\)
\(=110^2\)
![](https://rs.olm.vn/images/avt/0.png?1311)
a) Ta có: A= \(\frac{35^3+13^3}{48}-35\cdot13\)=\(\frac{\left(35+13\right)\left(35^2-35\cdot13+13^2\right)}{48}-35\cdot13\)
=\(35^2-35\cdot13+13^2+35\cdot13\)=\(35^2+13^2=1394\)
b) Ta có: B=\(\frac{68^3-52^3}{16}+68\cdot52\)=\(\frac{\left(68-52\right)\left(68^2+68\cdot52+52^2\right)}{16}+68\cdot52\)
=\(68^2+2\cdot68\cdot52+52^2\)= \(\left(68+52\right)^2=120^2=14400\)
cho mk hỏi tại sao ở dòng thứ nhất là trừ 35.13 xong dưới lại là cộng
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(B=\frac{\left(68-52\right)\left(68^2+68.52+52^2\right)}{16}+68.52=\frac{16\left(68^2+68.52+52^2\right)}{16}+68.52\)
\(B=68^2+2.68.52+52^2=\left(68+52\right)^2=120^2\)
Câu tiếp theo làm tương tự
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
a: Sửa đề: \(A=\dfrac{35^3+13^3}{48}-35\cdot13\)
\(=\dfrac{\left(35+13\right)\left(35^2-35\cdot13+13^2\right)}{48}-35\cdot13\)
\(=35^2-2\cdot35\cdot13+13^2=22^2\)
b: \(B=\dfrac{\left(68-52\right)\left(68^2+68\cdot52+52^2\right)}{16}+68\cdot52\)
\(=68^2+2\cdot68\cdot52+52^2\)
\(=110^2\)
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
a: Ta có: \(A=\dfrac{35^3+13^3}{48}-35\cdot13\)
\(=35^2-35\cdot13+13^2-35\cdot13\)
\(=\left(35-13\right)^2\)
\(=22^2=484\)
b: Ta có: \(B=\dfrac{68^3-52^3}{16}+68\cdot52\)
\(=68^2+68\cdot52+52^2+68\cdot52\)
\(=\left(68+52\right)^2=14400\)
a: Sửa đề: \(A=\dfrac{35^3+13^3}{48}-35\cdot13\)
\(=\dfrac{\left(35+13\right)\left(35^2-35\cdot13+13^2\right)}{48}-35\cdot13\)
\(=35^2-2\cdot35\cdot13+13^2=22^2\)
b: \(B=\dfrac{\left(68-52\right)\left(68^2+68\cdot52+52^2\right)}{16}+68\cdot52\)
\(=68^2+2\cdot68\cdot52+52^2\)
\(=110^2\)