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Bài 1:
\(a,=6x^2+19x-7-6x^3-4x^2+7x=-6x^3+2x^2+26x-7\\ b,B=26\cdot\left(63^2+63\cdot37+37^2\right):26+63\cdot37\\ =63^2+63\cdot37+37^2+63\cdot37\\ =\left(63+37\right)^2=100^2=10000\)
Bài 2:
\(a,=x\left(y^2-25\right)=x\left(y-5\right)\left(y+5\right)\\ b,=\left(x-y\right)\left(x+2\right)\\ c,=\left(x-3\right)\left(x^2-4\right)=\left(x-2\right)\left(x-3\right)\left(x+2\right)\)
Bài 2:
c: \(=x^2\left(x-3\right)-4\left(x-3\right)\)
\(=\left(x-3\right)\left(x-2\right)\left(x+2\right)\)
a. \(3x\left(2x+1\right)=6x^2+3x\)
b. \(\left(12x^3-18x^2+6x\right):6x=2x^2-3x+1\)
c. \(\dfrac{7x+6}{5x-1}+\dfrac{8x-9}{5x-1}=\dfrac{15x-3}{5x-1}=\dfrac{3\left(5x-1\right)}{5x-1}=3\)
c: \(=\dfrac{x^3+2x+2x^2+2x+x^2-x+1}{\left(x+1\right)\left(x^2-x+1\right)}\)
\(=\dfrac{x^3+3x^2+3x+1}{\left(x+1\right)\left(x^2-x+1\right)}=\dfrac{x^2+2x+1}{x^2-x+1}\)
\(x\left(2-3x\right)+\left(3x^2-x^2\right):x\)
\(=2x-3x^2+3x^2-x\)
\(=x\)
\(2x\left(x-3y\right)-\left(8x^3y-12x^2y^2\right):2xy\)
\(=2x^2-6xy-4x^2+6xy\)
\(=-2x^2\)
a: ĐKXD: x<>0
\(\dfrac{14x^3+12x^2-14x}{2x}=\left(x+2\right)\left(3x-4\right)\)
=>\(\dfrac{2x\left(7x^2+6x-7\right)}{2x}=\left(x+2\right)\left(3x-4\right)\)
=>\(7x^2+6x-7=3x^2-4x+6x-8\)
=>\(7x^2+6x-7=3x^2+2x-8\)
=>\(4x^2+4x+1=0\)
=>\(\left(2x+1\right)^2=0\)
=>2x+1=0
=>x=-1/2(nhận)
b: \(\left(4x-5\right)\left(6x+1\right)-\left(8x+3\right)\left(3x-4\right)=15\)
=>\(24x^2+4x-30x-5-\left(24x^2-32x+9x-12\right)=15\)
=>\(24x^2-26x-5-24x^2+23x+12=15\)
=>-3x+7=15
=>-3x=8
=>\(x=-\dfrac{8}{3}\)
1) \(\left(3x-1\right)\left(2x+7\right)-\left(12x^3+8x^2-14x\right):2x\)
\(=6x^2+19x-7-6x^2-4x+7=15x\)
2) \(\left(63^3-37^3\right):26+63.37\)
\(=\left(63-37\right)\left(63^2+63.37+37^2\right):26+63.37\)
\(\left[26\left(63^2+63.37+37^2\right)\right]:26+63.37\)
\(63^2+2.63.37+37^2=\left(63+37\right)^2=100^2=10000\)
\(\left(3x-1\right)\left(2x+7\right)-\left(12x^3+8x^2-14x\right):2x\)
\(=6x^2+19x-7-2x\left(6x^2+4x-7\right):2x=6x^2+19x-7-\left(6x^2-4x+7\right)=15x\)
(3x - 1)(2x + 7) - (12x3 + 8x2 - 14x) : 2x
= 6x2 + 21x - 2x - 7 - (6x2 + 4x - 7)
= 6x2 + 21x - 2x - 7 - 6x2 - 4x + 7
= 6x2 - 6x2 + 21x - 2x - 4x - 7 + 7
= 5x