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sau bạn đăng tách ra cho mn cùng giúp nhé
a, \(\left(-2x^5+3x^2-4x^3\right):2x^2=-x^3+\frac{3}{2}-2x\)
b, \(\left(x^3-2x^2y+3xy^2\right):\left(-\frac{1}{2}x\right)=-\frac{x^2}{2}+xy-\frac{3y^2}{2}\)
c, \(\left(3x^2y^2+6x^3y^3-12xy^2\right):3xy=xy+2x^2y^2-4y\)
d, \(\left(4x^3-3x^2y+5xy^2\right):\frac{1}{2}x=2x^2-\frac{3xy}{2}+\frac{5y^2}{2}\)
e, \(\left(18x^3y^5-9x^2y^2+6xy^2\right):3xy^2=6x^2y^3-3x+2\)
f, \(\left(x^4+2x^2y^2+y^4\right):\left(x^2+y^2\right)=\left(x^2+y^2\right)^2:\left(x^2+y^2\right)=x^2+y^2\)
a, \(=12x^5+9x^3y^2-6x^2y^3-20x^4y-15x^2y^3-10xy^4-24x^3y^2-18xy^4+12y^5\)
(tự rút gọn cái :P)
b, \(8x^3+4x^2y-2xy^2-y^3\)
\(=4x^2\left(2x+y\right)-y^2\left(2x+y\right)=\left(2x+y\right)^2\left(2x-y\right)\)
\(4x^2y^2-4x^2-4xy-y^2=4x^2y^2-\left(2x+y\right)^2\)
\(=\left(2x+y+2xy\right)\left(2xy-2x+y\right)\)
Mấy cái còn lại nhân tung ra là được mà :))))
\(a,x^3\left(3x^2-x-\dfrac{1}{2}\right)\)
\(=3x^5-x^4-\dfrac{1}{2}x^3\)
\(b,\left(5xy-x^2+y\right).\dfrac{2}{5xy^2}\)
\(=\dfrac{2}{y}-\dfrac{2x}{5y^2}+\dfrac{2}{xy}\)
\(c,\left(4x^3-3xy^2+2xy\right)\left(-\dfrac{1}{3}x^2y\right)\)
\(=-\dfrac{4x^5y}{3}+x^3y^3-\dfrac{2x^3y^2}{3}\)
Bài 3:
3: \(6x\left(x-y\right)-9y^2+9xy\)
\(=6x\left(x-y\right)+9xy-9y^2\)
\(=6x\left(x-y\right)+9y\left(x-y\right)\)
\(=\left(x-y\right)\left(6x+9y\right)\)
\(=3\left(2x+3y\right)\left(x-y\right)\)
Bài 4:
d. \(\left(x-3y\right)\left(3x^2+y^2+5xy\right)\)
\(=3x^3+xy^2+5x^2y-9x^2y-3y^3-15xy^2\)
\(=3x^3-14xy^2-4x^2y-3y^3\)
Bài 2:
a. \(x^2-y^2-5x+5y\)
\(=\left(x-y\right)\left(x+y\right)-5\left(x-y\right)\)
\(=\left(x+y-5\right)\left(x-y\right)\)
b. \(x^3-x^2-4x^2+8x-4\)
\(=x^2\left(x-1\right)-4\left(x^2-2x+1\right)\)
\(=x^2\left(x-1\right)-4\left(x-1\right)^2\)
\(=\left(x-1\right)\left[x^2-4\left(x-1\right)\right]\)
\(=\left(x-1\right)\left(x^2-4x+4\right)\)
\(=\left(x-1\right)\left(x-2\right)^2\)
Bài 3:
\(87^2+26.87+13^2\)
\(=\left(87+ 13\right)^2\)
\(=100^2\)
\(=10000\)
Bài 1:
a. \(3x^2\left(5x^2-4x+3\right)\)
\(=15x^4-12x^3+9x^2\)
b. \(-5xy\left(3x^2y-5xy-y^2\right)\)
\(=-15x^3y^2+25x^2y^2+5xy^3\)
c. \(\left(5x^2-4x\right)\left(x-3\right)\)
\(=5x^3-19x^2-4x^2+12x\)
Đáp án:
a.3x³−5x²+7xa.3x³−5x²+7x
b.−4x²y−10x²y+2xyb.−4x²y−10x²y+2xy
c.−x³+2x²+29x+20c.−x³+2x²+29x+20
d.2x⁴−3x³+2x²+3x−4d.2x⁴−3x³+2x²+3x−4
e.x²−4y²e.x²−4y²
h.2x²−6x+13h.2x²−6x+13
g.3xy⁴−12y²+2x²yg.3xy⁴−12y²+2x²y
f.−2x²y³+y−3f.−2x²y³+y−3
Giải thích các bước giải:
a.3x.(x²−5x+7)a.3x.(x²−5x+7)
=3x³−5x²+7x=3x³−5x²+7x
b.−2xy.(2x³+5x−1)b.−2xy.(2x³+5x−1)
=−4x⁴y−10xy²+2xy=−4x⁴y−10xy²+2xy
c.(x+4).(−x²+6x+5)c.(x+4).(−x²+6x+5)
=−x³+6x²+5x−4x²+24x+20=−x³+6x²+5x−4x²+24x+20
=−x³+2x²+29x+20=−x³+2x²+29x+20
d.(x²−1).(2x²−3x+4)d.(x²−1).(2x²−3x+4)
=2x⁴−3x³+4x²−2x²+3x−4=2x⁴−3x³+4x²−2x²+3x−4
=2x⁴−3x³+2x2+3x−4=2x⁴−3x³+2x2+3x−4
e.(x+2y).(x−2y)e.(x+2y).(x−2y)
=x²−(2y)²=x²−(2y)²
=x²−4y²=x²−4y²
h.(3x−1)²−7(x²+2)h.(3x−1)²−7(x²+2)
=9x²−6x+1−7x²−14=9x²−6x+1−7x²−14
=2x²−6x+13=2x²−6x+13
g.(6x²g.(6x²y⁵−xy³+4x³y²):2xy−xy³+4x³y²):2xy
=3xy⁴−12y²+2x²y=3xy⁴−12y²+2x²y
f.(−12x³y⁴+6xy²−18xy):6xyf.(−12x³y⁴+6xy²−18xy):6xy
=−2x³y³+y−3
a: \(=15x^4-12x^3+9x^2\)
c: \(=5x^3-15x^2-4x^2+12x\)
\(=5x^3-19x^2+12x\)
còn câu b và d sao ak