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a) \(x\left(x-3\right)\left(x+3\right)-\left(x^2-2\right)\left(x^2+2\right)\)
\(=x\left(x^2-9\right)-x^4+4\)
\(=x^3-9x-x^4+4\)
\(=-x^4+x^3-9x+4\)
A=a(a+b)-b(a+b)=(a+b)(a-b)=a2-b2(hằng đẳng thức 3)
B=(3x+2)2+(3x-2)2-2(9x2-4)+x
=(3x+2)2+(3x-2)2-2(3x-2)(3x+2)+x
=[(3x+2)-(3x-2)]2+x
=42+x
=16+x
a. \(A=9x^2-30x+25-4x^2+12x-9+16-4x^2\)
\(=x^2-18x+32\)
b. \(B=25x^2-70x+49-\left(4x+3\right)\left(4x^2+12x+9\right)-3x^3+9x^2+5x-15\)
\(=25x^2-70x+49-\left(16x^3+48x^2+36x-12x^2-36x-27\right)-3x^3+9x^2+5x-15\)
\(=-19x^3+-2x^2-65x+61\)
Chúc em học tốt ^^
b: \(\Leftrightarrow x\left(x^3-2x^2+10x-20\right)=0\)
\(\Leftrightarrow x\left(x-2\right)=0\)
hay \(x\in\left\{0;2\right\}\)
c: \(\Leftrightarrow\left(2x-3-x-5\right)\left(2x-3+x+5\right)=0\)
=>(x-8)(3x+2)=0
hay \(x\in\left\{8;-\dfrac{2}{3}\right\}\)
d: \(\Leftrightarrow x^2\left(x-1\right)-4\left(x-1\right)^2=0\)
\(\Leftrightarrow\left(x-1\right)\left(x^2-4x+4\right)=0\)
\(\Leftrightarrow\left(x-1\right)\left(x-2\right)^2=0\)
=>x=1 hoặc x=2
a: \(=4x^3\left(x+1\right)-x\left(x+1\right)\)
\(=x\left(x+1\right)\left(4x^2-1\right)\)
\(=x\left(x+1\right)\left(2x-1\right)\left(2x+1\right)\)
b: \(=x^4\left(x^2-1\right)-9x^2\left(x-1\right)\)
\(=x^2\cdot\left(x-1\right)\left[x^2\left(x+1\right)-9\right]\)
\(=x^2\left(x-1\right)\left(x^3+x-9\right)\)
d: \(=\left(xy+4\right)^2-\left(2x+2y\right)^2\)
\(=\left(xy+4-2x-2y\right)\left(xy+4+2x+2y\right)\)
\(=\left[x\left(y-2\right)-2\left(y-2\right)\right]\left[x\left(y+2\right)+2\left(y+2\right)\right]\)
\(=\left(y-2\right)\left(x-2\right)\left(y+2\right)\left(x+2\right)\)
e: \(=\left(ab-xy-bx+ay\right)\left(ab-xy+bx-ay\right)\)
\(=\left[a\left(b+y\right)-x\left(b+y\right)\right]\left[b\left(a+x\right)-y\left(a+x\right)\right]\)
\(=\left(b+y\right)\left(a-x\right)\left(a+x\right)\left(b-y\right)\)
\(a,\left(a+2\right)^2-\left(a+2\right)\left(a-2\right)\)
\(=a^2+4x+4-a^2+4\)
\(=4x+8\)
\(=4\left(x+2\right)\)
\(b,\left(a+b\right)^2-\left(a-b\right)^2\)
\(=a^2+2ab+b^2-\left(a^2-2ab+b^2\right)\)
\(=a^2+2ab+b^2-a^2+2ab-b^2\)
\(=4ab\)
\(c,\left(3x+4\right)^2-10x-\left(x+4\right)\left(x-4\right)\)
\(=9x^2+24x+16-10x-x^2+16\)
\(=8x^2+14x+32\)
\(=2\left(4x^2+7x+16\right)\)
thanks ban nha ^^