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a. -\(-16x^2+8xy-y^2+49\)
= \(\left(-\left(4x\right)^2+8xy-y^2\right)+49\)
= \(-\left(\left(4x^2\right)-8xy+y^2\right)+49\)
= \(-\left(4x-y\right)^2+49\)
b. \(y^2\left(x^2+y\right)-zx^2-zy\)
= \(y^2\left(x^2+y\right)-z\left(x^2+y\right)\)
= \(\left(x^2+y\right)\left(y^2-z\right)\)
_16x2+8xy_y2+49
=( _(4x)2+2 × 4 × xy _ y2 )+ 72
= _((4x)2_ 2×4×x × xy +y2)+72
= _(4x_y)2+72
=72_(4x_y)2
= (7_(4x_y))×(7+(4x_y))
= (7_4x+y)×(7+4x_y)
2)y2×(x2+y)_zx2_zy
=y×(x2+y)_z(x2+y)
= ( x2+y)×(y_z)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(16x^2+y^2+4y-16y-8xy\)
\(=\left(16x^2-8xy+y^2\right)+4y-16y\)
\(=\left(4x+y\right)^2-12y\)
\(=\left(4x+y-\sqrt{12y}\right)\left(4x+y-\sqrt{12y}\right)\)
P/S : Sai thì thôi nha!
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a) Ta có: \(4x^2-28xy+49y^2\)
\(=\left(2x\right)^2-2\cdot2x\cdot7y+\left(7y\right)^2\)
\(=\left(2x-7y\right)^2\)
b) Ta có: \(x^2+8xy+16y^2\)
\(=x^2+2\cdot x\cdot4y+\left(4y\right)^2\)
\(=\left(x+4y\right)^2\)
c) Ta có: \(x^2-12x+36\)
\(=x^2-2\cdot x\cdot6+6^2\)
\(=\left(x-6\right)^2\)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(-16x^2+8xy-y^2+49\)
\(=7^2-\left(4x-y\right)^2\)
\(=\left(7-4x+y\right)\left(7+4x-y\right)\)
\(-16x^2+8xy-y^2+49\)
\(=49-\left(16x^2-8xy+y^2\right)\)
\(=7^2-\left(4x-y\right)^2\)
\(=\left(7-4x+y\right)\left(7+4x-y\right)\)