Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
\(a,\left(6x+1\right)\left(x+2\right)-2x\left(3x-5\right)\)
\(=6x^2+12x+x+2-6x^2+10x\)
\(=23x+2\)
a) (6x + 1)(x + 2) - 2x(3x - 5)
= 6x2 + 12x + x + 2 - 6x2 + 10x
= (6x2 - 6x2) + (12x + x + 10x) + 2
= 23x + 2
b) (2x - 1)2 - (2x - 3)(2x + 3)
= 4x2 - 4x + 1 - 4x2 + 9
= (4x2 - 4x2) - 4x + (1 + 9)
= -4x + 10
c) (2x - 3)3 - (3x + 1)(5 - 4x) - 16x2
= 8x3 - 36x2 + 54x - 15x + 12x2 - 5 + 4x - 16x2
= 8x3 - (36x2 - 12x2 + 16x2) + (54x - 15x + 4x) - 5
= 8x3 - 40x2 + 43x - 5
d) (3x + 2) - (x - 5) - x(3x - 13)
= 3x + 2 - x + 5 - 3x2 + 13x
= (3x - x + 13x) + (2 + 5) - 3x2
= 15x + 7 - 3x2
a: \(=x^3-27-x^3-27x+x+27=-26x\)
b: \(=x^2-14x-10x^2+20x-10=-9x^2+6x-10\)
c: \(\Leftrightarrow2x^2-4x-4x^2-6x+2x+3=0\)
=>3=0(vô lý)
a) 9x^2-6x+1+ 12x^2-2+ 4x^2-4x+1
=25x^2-10x
b) (x^2+2x+1)(x-3) -(x^3-27)
=x^3-3-x^3+27
=24
Nhớ ấn cho mfinh nhé, mình chưa có điểm cộng nào cảm ơn
1)a)3(2x-1)(3x-1)-(2x-3)(9x-1)=0
<=>18x2-15x+1-18x2+29x-3=0
<=>14x-2=0
<=>14x=2
<=>x=1/7
b)4(x+1)2+(2x-1)2-8(x-1)(x+1)=11
<=>4x2+8x+4+4x2-4x+1-8x2+8=11
<=>4x+13=11
<=>4x=11-13
<=>4x=-2
<=>x=-1/2
c)Sai đề phải là dấu - chứ không phải +
(x-3)(x2+3x+9)-x(x-2)(x+2)=1
<=>x3-27-x3+4x=1
<=>4x=1+27
<=>4x=28
<=>x=7
2)a)(2x-3y)(2x+3y)-4(x-y)2-8xy
=4x2-9y2-4x2+8xy-4y2-8xy
=-13y2
b)(x-2)3-x(x+1)(x-1)+6x(x-3)
=x3-6x2+12x+8-x3+x+6x2-18x
=8-5x
c)(x-2)(x2-2x+4)(x+2)(x2+2x+4)
=(x-2)(x2+2x+4)(x+2)(x2-2x+4)
=(x3-8)(x3+8)
=x6-64
a/\(\left(2x+1\right)^2-\left(2x+3\right)\left(2x-3\right).\)
\(=\left(4x^2+4x+1\right)-\left(4x^2-9\right)\)
\(=4x^2+4x+1-4x^2+9\)
\(=4x+10\)
b/\(4\left(x-1\right)\left(x+3\right)+5\left(2x+1\right)^2-2\left(5-3x\right)^2\)
\(=4\left(x^2+3x-x-3\right)+5\left(4x^2+4x+1\right)-2\left(25-30x+9x^2\right)\)
\(=4\left(x^2+2x-3\right)+5\left(4x^2+4x+1\right)-2\left(25-30x+9x^2\right)\)
\(=4x^2+8x-12+20x^2+20x+5-50+60x-18x^2\)
\(=6x^2+88x-57\)
mik tính toán cẩu thả lắm ạ có j sai ib ạ. Cảm ơn :3
a) (2x+1)^2+2(4x^2-2)+(2x-1)^2=4x2+4x+1+8x2-4+4x2-4x+1=16x2-2
`Answer:`
`a)`
`A=5(x+1)^2-3(x-3)^2-4(x^2-4)`
`=>A=5(x^2+2x+1)-3(x^2-6x+9)-4x^2+16`
`=>A=5x^2+10x+5-3x^2+18x-27-4x^2+16`
`=>A=(5x^2-3x^2-4x^2)+(10x+18x)+(5-27+16)`
`=>A=-2x^2+28x-6`
`b)`
`B=5(x+1)^2-3(x-3)^2-4(x+2)(x-2)`
`=2x(3x+5)-3(3x+5)-2x(x^2-4x+4)-[(2x)^2-3^2]`
`=6x^2+10x-9x-15-2x^3+8x^2-8x-4x^2+9`
`=(6x^2-4x^2+8x^2)-2x^3+(10x-9x-8x)+(-15+9)`
Thay `x=-7` vào ta được:
`B=10(-7)^2-2(-7)^3-7(-7)-6`
`=>B=10.49-2(-343)+49-6`
`=>B=490+686+49-6`
`=>B=1219`
a) (2x - 1)(3x + 5) - 2(-4x + 1)2 = 6x2 + 10x - 3x - 5 - 2(16x2 - 8x + 1) = 6x2 - 3x - 5 - 32x2 + 16x - 2 = -26x2 + 13x - 7
b) \(\frac{x^2-16}{4x-x^2}=\frac{\left(x-4\right)\left(x+4\right)}{-x\left(x-4\right)}=-\frac{x+4}{x}\)
c) \(\frac{2x-9}{x^2-5x+6}+\frac{2x+1}{x-3}+\frac{x+3}{2-x}\)
= \(\frac{2x-9}{x^2-2x-3x+6}+\frac{\left(2x+1\right)\left(x-2\right)}{\left(x-3\right)\left(x-2\right)}-\frac{\left(x+3\right)\left(x-3\right)}{\left(x-3\right)\left(x-2\right)}\)
= \(\frac{2x-9+2x^2-3x-2-x^2+9}{\left(x-3\right)\left(x-2\right)}\)
= \(\frac{x^2-x-2}{\left(x-3\right)\left(x-2\right)}\)
= \(\frac{x^2-2x+x-2}{\left(x-3\right)\left(x-2\right)}\)
= \(\frac{\left(x+1\right)\left(x-2\right)}{\left(x-3\right)\left(x-2\right)}=\frac{x+1}{x-3}\)
d) (x - 1)3 - (x + 1)3 + 6(x + 1)(x - 1)
= (x - 1 - x - 1)[(x - 1)2 + (x - 1)(x + 1) + (x + 1)2] + 6(x2 - 1)
= -2(x2 - 2x + 1 + x2 - 1 + x2 + 2x + 1) + 6x2 - 6
= -2(3x2 + 1) + 6x2 - 6
= -6x2 - 2 + 6x2 - 6
= -8
e) (2x + 7)2 - (4x + 14)(2x - 8) + (8 - 2x)2
= (2x + 7)2 - 2(2x + 7)(2x - 8) + (2x - 8)2
= (2x + 7 - 2x + 8)2
= 152 = 225
a. gọi phần đầu đấy là A nhá, để đỡ cần viết lại
A=...............
= (3x+5)2 + ( 3x-5)2 - 9x2 -4
= (9x2 +30x + 25 ) + ( 9x2 -30x+ 25 ) - 9x2 -4
= 9x2 +30x + 25 + 9x2 -30x+25-9x2 -4
= 9x2 + 46
sai thì thôi nhé. bạn nên kiểm tra lại
d. (2x-1)*(4x2 + 2x +1 ) - 8x*( x2 +1) - 5
= 8x3 -1 - 8x3 -8x-5
= -8x-6
= -2(4x+3)
sai nhé. bạn nên kiểm tra lại
a) \(x\left(x-1\right)+2\left(x-2\right)-\left(9-x^2\right)\)
\(=\)\(x^2\)\(-\)\(x\)\(+\)\(2x\)\(-\)\(4\)\(-\)\(9\)\(+\)\(x^2\)
\(=\)\(x-13\)
b) \(\left(x+3\right)\left(2x-1\right)-\left(3x+5\right)\left(2x-1\right)\)
\(=\)\(2x^2\)\(-\)\(x\)\(+\)\(6x\)\(-\)\(3\)\(-\)\(\left(6x^2-3x+10x-5\right)\)
\(=\)\(2x^2\)\(+\)\(5x\)\(-\)\(3\)\(-\)\(6x^2\)\(+\)\(3x\)\(-\)\(10x\)\(+\)\(5\)
\(=\)\(-4x^2\)\(-\)\(2x\)\(+\)\(2\)
Cách khác :
b) \(\left(x+3\right)\left(2x-1\right)-\left(3x+5\right)\left(2x-1\right)\)
\(=\)\(\left(2x-1\right)\left(x+3-3x-5\right)\)
\(=\)\(\left(2x-1\right)\left(-2x-2\right)\)
\(=\)\(-4x^2\)\(-\)\(4x\)\(+\)\(2x\)\(+\)\(2\)
\(=\)\(-4x^2\)\(-\)\(2x\)\(+\)\(2\)
a ) x ( x - 1 ) + 2 ( x - 2 ) - ( 9 + x^2 )
=( x^2 - x ) + ( 2x - 4 ) - ( 9 + x^2 )
= x^2 - x + 2x - 4 - 9 - x^2
= -x + 2x - 13
= x - 13
b ) ( x + 3 ) x ( 2x - 1 ) = ( x + 3 ) . ( 2x - 1 ) hay = ( x + 3 ) . x(2x - 1 )