thu gọn
-2x.(xy)3.1/4(-y)3 / (-2/5)3.(x2y)5. (5x)2
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a: Ta có: \(x^2-4x\left(3x-4\right)+7x-5\)
\(=x^2-12x^2+16x+7x-5\)
\(=-11x^2+23x-5\)
b: Ta có: \(7x\left(x^2-5\right)-3x^2y\left(xy-6y^2\right)\)
\(=7x^3-35x-3x^3y^2+18x^2y^3\)
c: Ta có: \(\left(5x+4\right)\left(2x-7\right)\)
\(=10x^2-35x+8x-28\)
\(=10x^2-27x-28\)
Thu gọn đa thức
a,A=2x2 +x-\(\dfrac{1}{2}\)x2+5x+3
b,B=5xy+\(\dfrac{1}{2}\)x2y-\(\dfrac{2}{3}\)xy+2x2y
a: \(A=\dfrac{3}{2}x^2+6x+3\)
b: \(B=5xy-\dfrac{2}{3}xy+\dfrac{1}{2}x^2y+2x^2y=\dfrac{5}{2}x^2y+\dfrac{13}{3}xy\)
a) \(2x^2+x-\dfrac{1}{2}x^2+5x+3\)\(\)
= \(\left(2x-\dfrac{1}{2}x^2\right)+\left(x+5x\right)+3\)
= \(\dfrac{3}{2}x^2+6x+3\)
Vậy A = \(\dfrac{3}{2}x^2+6x+3\)
A)\(5xyz.4x^2y^2.\left(-2x^3y\right)=\left(5.4.\left(-2\right)\right).\left(xx^2x^3\right).\left(yy^2y\right)=\left(-40\right)x^6y^4\)
- BẬC : 10
- HỆ SỐ: -40
B) \(-xy.\left(\frac{1}{2}x^3y^4\right).\left(\frac{-4}{7}x^2y^5\right)=\left(\frac{1}{2}.\frac{-4}{7}.\left(-1\right)\right).\left(xx^3x^2\right).\left(y^4y^5y\right)=\frac{2}{7}x^6y^{10}\)
- BẬC : 16
- HỆ SỐ: 2/7
C) \(\frac{5}{3}x^2y^4.\left(\frac{-6}{5}xy^3\right).\left(-xy\right)=\left(\frac{5}{3}.\frac{-6}{5}.\left(-1\right)\right).\left(x^2xx\right).\left(y^4y^3y\right)=2x^4y^8\)
- BẬC : 12
- HỆ SỐ : 2
D) \(\left(\frac{-1}{3}x^2y^5\right).\left(\frac{3}{4}xy\right).5x=\left(\frac{-1}{3}.\frac{3}{4}.5\right).\left(x^2xx\right).\left(y^5y\right)=\frac{-5}{4}x^4y^6\)
- BẬC : 10
- HỆ SỐ : -5 /4
CHÚC BN HỌC TỐT!!
a, 2xy +2x2 - 4xy2 - 2 ; b, -3x2y2 -2x2y + y ; c, 3x3 - 2y - 3
`#3107`
`a)`
`(6x - 2)^2 + 4(3x - 1)(2 + y) + (y + 2)^2 - (6x + y)^2`
`= [(6x - 2)^2 - (6x + y)^2] + 4(3x - 1)(2 + y) + (2 + y)^2`
`= (6x - 2 - 6x - y)(6x -2 + 6x + y) + (2 + y)*[ 4(3x - 1) + 2 + y]`
`= (2 - y)(12x + y - 2) + (2 + y)*(12x - 4 + 2 + y)`
`= (2 - y)(12x + y - 2) + (2 + y)*(12x + y - 2)`
`= (12x + y - 2)(2 - y + 2 + y)`
`= (12x + y - 2)*4`
`= 48x + 4y - 8`
`b)`
\(5(2x-1)^2+2(x-1)(x+3)-2(5-2x)^2-2x(7x+12)\)
`= 5(4x^2 - 4x + 1) + 2(x^2 + 2x - 3) - 2(25 - 20x + 4x^2) - 14x^2 - 24x`
`= 20x^2 - 20x + 5 + 2x^2 + 4x - 6 - 50 + 40x - 8x^2 - 14x^2 - 24x`
`= - 51`
`c)`
\(2(5x-1)(x^2-5x+1)+(x^2-5x+1)^2+(5x-1)^2-(x^2-1)(x^2+1)\)
`= [ 2(5x - 1) + x^2 - 5x + 1] * (x^2 - 5x + 1) + (5x - 1)^2 - [ (x^2)^2 - 1]`
`= (10x - 2 + x^2 - 5x + 1) * (x^2 - 5x + 1) + (5x - 1)^2 - x^4 + 1`
`= (x^2 + 5x - 1)(x^2 - 5x + 1) + (5x - 1)^2 - x^4 + 1`
`= x^4 - (5x - 1)^2 + (5x - 1)^2 - x^4 + 1`
`= 1`
`d)`
\((x^2+4)^2-(x^2+4)(x^2-4)(x^2+16)-8(x-4)(x+4)\)
`= (x^2 + 4)*[x^2 + 4 - (x^2 - 4)(x^2 + 16)] - 8(x^2 - 16)`
`= (x^2 + 4)(x^4 + 12x^2 - 64) - 8x^2 + 128`
`= x^6 + 16x^4 - 16x^2 - 256 - 8x^2 + 128`
`= x^6 + 16x^4 - 24x^2 - 128`
a: \(=-2\cdot\dfrac{1}{4}\cdot3\cdot x^2y^2\cdot xy\cdot xy^3=-\dfrac{3}{2}x^4y^6\)
b: \(=4x^6y^2\cdot xy^2\cdot\dfrac{1}{2}y^5=2x^7y^9\)
Bài 2:
a: Ta có: \(2\left(5x-8\right)-3\left(4x-5\right)=4\left(3x-4\right)+11\)
\(\Leftrightarrow10x-16-12x+15=12x-16+11\)
\(\Leftrightarrow-14x=-4\)
hay \(x=\dfrac{2}{7}\)
b: Ta có: \(2x\left(6x-2x^2\right)+3x^2\left(x-4\right)=8\)
\(\Leftrightarrow12x^2-4x^3+3x^3-12x^2=8\)
\(\Leftrightarrow x^3=-8\)
hay x=-2
Bài 1:
a: Ta có: \(I=x\left(y^2-xy^2\right)+y\left(x^2y-xy+x\right)\)
\(=xy^2-x^2y^2+x^2y^2-xy^2+xy\)
\(=xy\)
=1
b: Ta có: \(K=x^2\left(y^2+xy^2+1\right)-\left(x^3+x^2+1\right)\cdot y^2\)
\(=x^2y^2+x^3y^2+x^2-x^3y^2-x^2y^2-y^2\)
\(=x^2-y^2\)
\(=\dfrac{1}{4}-\dfrac{1}{4}=0\)
\(1,\\ a,A=4x^2\left(-3x^2+1\right)+6x^2\left(2x^2-1\right)+x^2\\ A=-12x^4+4x^2+12x^2-6x^2+x^2=-x^2=-\left(-1\right)^2=-1\\ b,B=x^2\left(-2y^3-2y^2+1\right)-2y^2\left(x^2y+x^2\right)\\ B=-2x^2y^3-2x^2y^2+x^2-2x^2y^3-2x^2y^2\\ B=-4x^2y^3-4x^2y^2+x^2\\ B=-4\left(0,5\right)^2\left(-\dfrac{1}{2}\right)^3-4\left(0,5\right)^2\left(-\dfrac{1}{2}\right)^2+\left(0,5\right)^2\\ B=\dfrac{1}{8}-\dfrac{1}{4}+\dfrac{1}{4}=\dfrac{1}{8}\)
\(2,\\ a,\Leftrightarrow10x-16-12x+15=12x-16+11\\ \Leftrightarrow-14x=-4\\ \Leftrightarrow x=\dfrac{2}{7}\\ b,\Leftrightarrow12x^2-4x^3+3x^3-12x^2=8\\ \Leftrightarrow-x^3=8=-2^3\\ \Leftrightarrow x=2\\ c,\Leftrightarrow4x^2\left(4x-2\right)-x^3+8x^2=15\\ \Leftrightarrow16x^3-8x^2-x^3+8x^2=15\\ \Leftrightarrow15x^3=15\\ \Leftrightarrow x^3=1\Leftrightarrow x=1\)
= 1/2x4y6 / -8/5x4y5
= -5/16y
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