Tính: (4x2 — 9y2) : 2x — 3y
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(4x2 – 9y2) : (2x – 3y)
(Sử dụng HĐT để phân tích số bị chia thành tích)
= [(2x)2 – (3y)2] : (2x – 3y)
(Xuất hiện hằng đẳng thức (3))
= (2x – 3y)(2x + 3y) : (2x – 3y)
= 2x + 3y.
b) \(\left(4x^2+4xy+y^2\right):\left(2x+y\right)=\dfrac{\left(2x+y\right)^2}{2x+y}=2x+y\)
c) \(\left(x^2-6xy+9y^2\right):\left(3y-x\right)=\dfrac{\left(3y-x\right)^2}{3y-x}=3y-x\)
\(a,=2xy\left(\dfrac{1}{3}x-y+2\right)\\ b,=\left(2x-3y\right)\left(2x+3y\right)-\left(2x+3y\right)=\left(2x+3y\right)\left(2x-3y-1\right)\)
b: Ta có: \(4x^2-9y^2-2x-3y\)
\(=\left(2x-3y\right)\left(2x+3y\right)-\left(2x+3y\right)\)
\(=\left(2x+3y\right)\left(2x-3y-1\right)\)
\(A=x^3-8-128-x^3=-136\\ B=8x^3+27y^3-27x^3+8y^3=-19x^3+35y^3\)
\(A=\left(x-2\right)\left(x^2+2x+4\right)-\left(128+x^3\right)=x^3-8-128-x^3=-136\)
\(B=\left(2x+3y\right)\left(4x^2-6xy+9y^2\right)-\left(3x-2y\right)\left(9x^2+6xy+4y^2\right)=8x^3+27y^3-27x^3+8y^3=-19x^3+35y^3\)
a ) \(\left(4x^2+4xy+y^2\right):\left(2x+y\right)\)
\(=\left(2x+y\right)^2:\left(2x+y\right)\)
\(=2x+y\)
b ) \(\left(27x^3+1\right):\left(3x+1\right)\)
\(=\left(3x+1\right)\left(9x^2-3x+1\right):\left(3x+1\right)\)
\(=9x^2-3x+1\)
c ) \(\left(x^2-6xy+9y^2\right):\left(3y-x\right)\)
\(=\left(x-3y\right)^2:\left(3y-x\right)\)
\(=\left(3y-x\right)^2:\left(3y-x\right)\)
\(=3y-x\)
d ) \(\left(8x^3-1\right):\left(4x^2+2x+1\right)\)
\(=\left(2x-1\right)\left(4x^2+2x+1\right):\left(4x^2+2x+1\right)\)
\(=2x-1\)
:D
a: Ta có: \(\left(2x-1\right)^2-2\left(2x-3\right)^2+4\)
\(=4x^2-4x+1-2\left(4x^2-12x+9\right)+4\)
\(=4x^2-4x+5-8x^2+24x-18\)
\(=-4x^2+20x-13\)
b: \(\left(3x+2\right)^2+2\left(3x+2\right)\left(1-2y\right)+\left(1-2y\right)^2\)
\(=\left(3x+2+1-2y\right)^2\)
\(=\left(3x-2y+3\right)^2\)
a: \(\left(2x-1\right)^2-2\left(2x-3\right)^2+4\)
\(=4x^2-4x+1+4-2\left(4x^2-12x+9\right)\)
\(=4x^2-4x+5-8x^2+24x-18\)
\(=-4x^2+20x-13\)
e: \(\left(2x+3y\right)\left(4x^2-6xy+9y^2\right)=8x^3+27y^3\)
a. \(x^2-10x+25=\left(x-5\right)^2\)
b.\(4-4x^2+x^4=\left(2-x^2\right)^2\)
c. \(x^2-6y+9y^2=\left(x-3y\right)^2\)
d. \(\left(2x+y^2\right)\left(2x-y^2\right)=4x^2-y^4\)
Viết dưới dạng phân thức cho dễ nhìn
\(\frac{4x^2-9y^2}{2x-3y}=\frac{\left(2x-3y\right)\left(2x+3y\right)}{2x-3y}=2x+3y\)