1:thu gọn biểu thức
a,8X-5X-19X
b,(-ab)-ab
c,(-X)-X-3X
d,(-XYZ)+3XYZ
2:tìm X
,(X+1)+(X+3)+(X+5)+...+(X+99)=0
rút gọn các biểu thức
a) (x+1)2-(x-1)2-3(x+1)(x-1)
b) 5(x+2)(x-2) -1/2(6-8x)2+17
a) Ta có: \(\left(x+1\right)^2-\left(x-1\right)^2-3\left(x+1\right)\left(x-1\right)\)
\(=x^2+2x+1-x^2+2x-1-3\left(x^2-1\right)\)
\(=4x-3x^2+3\)
\(=-3x^2+4x+3\)
b) Ta có: \(5\left(x+2\right)\left(x-2\right)-\dfrac{1}{2}\left(6-8x\right)^2+17\)
\(=5\left(x^2-4\right)-\dfrac{1}{2}\left(64x^2-96x+36\right)+17\)
\(=5x^2-20-32x^2+48x-16+17\)
\(=-27x^2+48x-19\)
thu gọn đa thức
a. 3x(x-5)-(x-2)7x
b. (x+4)(x-4)-2x(3-x)
c. (3x-7)(-2x+1)-8x(6-x)
a, 3x(x-5)-(x-2)7x
= 3x2 - 15x -7x2 - 14x
= -4x2 - 29x
= -x(4x+ 29)
b,(x+4)(x+4)-2x(3-x)
= x2 - 42 - 6x + 2x2
= 3x2 - 6x - 16
c,(3x-7)(-2x+1)-8x(6-x)
= -6x2 + 3x +14x -7 - 48x + 8x2
= 2x2 - 31x - 7
thu gọn đa thức và tìm bậc của đơn thức
a)6x^2y^5.(-2).x^3y^2z
b)(1/5.x^3y^4).(10/9.xyz)
\(a,-12x^5y^7z\) có bậc là 13
\(b,\dfrac{2}{9}x^4y^5z\) có bậc là10
thu gọn đa thức và tìm bậc của đơn thức
a)6x^2y^5.(-2).x^3y^2z
b)(1/5.x^3y^4).(10/9.xyz)
a: \(=6\cdot\left(-2\right)\cdot x^2y^5\cdot x^3y^2z=-12x^5y^7z\)
bậc là 13
b: \(=\dfrac{1}{5}\cdot\dfrac{10}{9}\cdot x^3y^4\cdot xyz=\dfrac{2}{9}x^4y^5z\)
bậc là 10
thu gọn đa thức và tìm bậc của đơn thức
a)6x^2y^5.(-2).x^7y^2z
b)(1/5.x^7y^4).(10/9.xyz)
a, \(=-12x^9y^7z\)bậc 17
b, \(=\dfrac{2}{9}x^8y^5z\)bậc 14
1. Thu gọn biểu thức
a) (x-3) ² + 3x (x-5)
b) (3x+2) ² - (x+3) (x-3)
2. Tìm x biết a) (x+4) ² - (x+2) (x-2)=5
b) (3x-1) ² _ (2x-3) (4x+1)= 5+x ²
1.
a) \(=x^2-6x+9+3x^2-15x=4x^2-21x+9\)
b) \(=9x^2+12x+4-x^2+9=8x^2+12x+13\)
2.
a) \(\Leftrightarrow x^2+8x+16-x^2+4-5=0\\ \Leftrightarrow8x=-15\\ \Leftrightarrow x=-\dfrac{15}{8}\)
b) \(\Leftrightarrow9x^2-6x+1-8x^2+12x-2x+3-5-x^2=0\\ \Leftrightarrow4x=1\\ \Leftrightarrow x=\dfrac{1}{4}\)
1,a,=x2−6x+8+3x2−15x=4x2−21x+8b,=9x2+12x+4−x2+9=8x2+12x+132,a,⇔x2+8x+16−x2+4=5⇔8x=−15⇔x=−158b,⇔9x2−6x+1−8x2−2x+12x+3−x2=5⇔4x=1⇔x=14
Tìm x
(4x+3)2+(3x-4)2+(2+5x)(2-5x)=x
Thu gọn biểu thức
a)(x-3)(x+3)-(x-3)2
b)(3x-1)2+2(3x-1)(2x+1)+(2x+1)2
giúp mình với ;-;
1) \(\Rightarrow16x^2+24x+9+9x^2-24x+16+4-25x^2=x\)
\(\Rightarrow x=29\)
2)
a) \(=x^2-9-x^2+6x-9=6x-18\)
b) \(=\left(3x-1+2x+1\right)^2=\left(5x\right)^2=25x^2\)
thu gọn biểu thức
a) (6x-2)2+4(3x-1)(2+y)+(y+2)2-(6x+y)2
b)5(2x-1)2+2(x-1)(x+3)-2(5-2x)2-2x(7x+12)
c)2(5x-1)(x2-5x+1)+(x2-5x+1)2+(5x-1)2-(x2-1)(x2+1)
d)(x2+4)2-(x2+4)(x2-4)(x2+16)-8(x-4)(x+4)
`#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`
bài 1 : Rút gọn biểu thức
a) 3x.(x-2)-5x(1-x)-8(x^2-3)
b) (7x-3) (2x+1) - (5x-2) (x+4)-9x^2 + 17x
\(a,3x\left(x-2\right)-5x\left(1-x\right)-8\left(x^2-3\right)\)
\(=3x^2-6x-5x+5x^2-8x^2+24\)
\(=\left(3x^2+5x^2-8x^2\right)+\left(-6x-5x\right)+24\)
\(=0-11x+24\)
\(=-11x+24\)
\(b,\left(7x-3\right)\left(2x+1\right)-\left(5x-2\right)\left(x+4\right)-9x^2+17x\)
\(=14x^2+7x-6x-3-5x^2-20x+2x+8-9x^2+17x\)
\(=\left(14x^2-5x^2-9x^2\right)+\left(7x-6x-20x+2x+17x\right)+\left(-3+8\right)\)
\(=0+0+5\)
\(=5\)