tim x
a,(x-3)^3-(x-3)(x^2+3x+9)+9(x+1)^2=4
b,x(x-5)(x+5)-(x+2)(x^2-2x+4)=17
tìm x thỏa mãn:
a) (x+2)(x+3)-(x-2)(x-5)=-4
b) (x+1)(x2-x+1)-x(x-3)(x+3)=8
c) 4x2-9=(3x+1)(2x-3)
d) (3x+1)2-4(x-1)2=0
a: Ta có: \(\left(x+2\right)\left(x+3\right)-\left(x-2\right)\left(x-5\right)=-4\)
\(\Leftrightarrow x^2+5x+6-x^2+7x-10=-4\)
\(\Leftrightarrow12x=0\)
hay x=0
b: Ta có: \(\left(x+1\right)\left(x^2-x+1\right)-x\left(x-3\right)\left(x+3\right)=8\)
\(\Leftrightarrow x^3+1-x^3+9x=8\)
\(\Leftrightarrow9x=7\)
hay \(x=\dfrac{7}{9}\)
c: Ta có: \(4x^2-9=\left(3x+1\right)\left(2x-3\right)\)
\(\Leftrightarrow\left(3x+1\right)\left(2x-3\right)-\left(2x-3\right)\left(2x+3\right)=0\)
\(\Leftrightarrow\left(2x-3\right)\left(3x+1-2x-3\right)=0\)
\(\Leftrightarrow\left(2x-3\right)\left(x-2\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{3}{2}\\x=2\end{matrix}\right.\)
tim gia tri cua bien thoa man mot dieu kien cho truoc
1) (x-2)^3-(x-3)*(x^2+3x+9)+6(x+1)^2=49
2) x(x+5)(x-5)-(x+2)(x^2-2x+4)=42
3) (x+3)^3-(x+1)^3=56
4) (3x-5)(5-3x)+9(x+1)^2=30
5) x(x+5)(x-5)-(x+2)(x^2-2x+4)=42
HO MIK VS A CAM ON MN
Bài 1:tìm x
a,(x+1)^3+(2-x)(4+2x+x^2)+3x(x+2)=17
b,(x+2)(x^2-2x+4)-x(x^2-2)=15
c,(x-3)^3-(x-3)(x^2+3x+9)+9(x+1)^2=15
d,x(x-5)(x+5)-(x+2)(x^2-2x+4)=3
\(a,\left(x+1\right)^3+\left(2-x\right)\left(4+2x+x^2\right)+3x\left(x+2\right)=17\)\(\Leftrightarrow x^3+3x^2+3x+1+8-x^3+3x^2+6x-17=0\)\(\Leftrightarrow6x^2+9x-8=0\)
\(\Leftrightarrow x^2+\dfrac{3}{2}x-\dfrac{4}{3}=0\)
\(\Leftrightarrow\left(x^2+\dfrac{3}{2}x+\dfrac{9}{16}\right)-\dfrac{9}{16}-\dfrac{4}{3}=0\)
\(\Leftrightarrow\left(x+\dfrac{3}{4}\right)^2=\dfrac{91}{48}\)
\(\Leftrightarrow\left[{}\begin{matrix}x+\dfrac{3}{4}=\sqrt{\dfrac{91}{48}}\\x+\dfrac{3}{4}=-\sqrt{\dfrac{91}{48}}\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=\sqrt{\dfrac{91}{48}}-\dfrac{3}{4}\\x=-\sqrt{\dfrac{91}{48}}-\dfrac{3}{4}\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{-9+\sqrt{273}}{12}\\x=-\dfrac{9+\sqrt{273}}{12}\end{matrix}\right.\)
b, \(\left(x+2\right)\left(x^2-2x+4\right)-x\left(x^2-2\right)=15\)
\(\Leftrightarrow x^3+8-x^3+2x-15=0\)
\(\Leftrightarrow2x=7\Rightarrow x=\dfrac{7}{2}\)
tìm x
a,(x+1)^3-(x-1)^3-6(x-1)^2=-10
b,x(x+5)(x-5)-(x+2)(x^2-2x+4)=42
c,(x-2)^3-(x-3)(x^2+3x+9)+6(x+1)^2=49
a) \(\left(x+1\right)^3-\left(x-1\right)^3-6\cdot\left(x-1\right)^2=10\)
\(\Rightarrow x^3+3x^2+3x+1-x^3+3x^2-3x+1-6\cdot\left(x^2-2x+1\right)=10\)
\(\Rightarrow6x^2+2-6x^2+12x-6=10\)
\(\Rightarrow12x-4=10\)
\(\Rightarrow12x=14\)
\(\Rightarrow x=\dfrac{7}{6}\)
b) \(x\left(x+5\right)\left(x-5\right)-\left(x+2\right)\left(x^2-2x+4\right)=42\)
\(\Rightarrow x\left(x^2-25\right)-\left(x^3+8\right)=42\)
\(\Rightarrow x^3-25x-x^3-8=42\)
\(\Rightarrow-25x-8=42\)
\(\Rightarrow-25x=50\)
\(\Rightarrow x=\dfrac{50}{-25}=-2\)
c) \(\left(x-2\right)^3-\left(x-3\right)\left(x^2+3x+9\right)+6\left(x+1\right)^2=49\)
\(\Rightarrow x^3-6x^2+12x-8-\left(x^3-27\right)+6\left(x^2+2x+1\right)=49\)
\(\Rightarrow x^3-6x^2+12x-8-x^3+27+6x^2+12x+6=49\)
\(\Rightarrow24x+25=49\)
\(\Rightarrow24x=24\)
\(\Rightarrow x=\dfrac{24}{24}=1\)
dùng hằng đẳng thức để làm nha. cần gấp, thanks nhìu
a) (x-1)^3+(2-x)(4+2x+x^2)+3x(x+2)=17
b) (x+2)(x^2-2x+4)-x(x^2-2)=15
c) (x-3)^3-(x-3)(x^2+3x+9)+9(x+1)^2=15
d) x(x-5)(x+5)-(x+2)(x^2-2x+4)=3
a,\(\Leftrightarrow\left(x-1\right)^3+\left(2-x\right)\left(4+2x+x^2\right)+3x\left(x+2\right)-17=0\)
\(\Leftrightarrow x^3-3x^2+3x-1+8-x^3+3x^2+6x-17=0\)
\(\Leftrightarrow9x-10=0\)
\(\Leftrightarrow x=\frac{10}{9}\)
b,\(\Leftrightarrow x^3+8-x^3+2x-15=0\)
\(\Leftrightarrow2x=7\)
\(\Leftrightarrow x=\frac{7}{2}\)
c,\(\Leftrightarrow x^3-9x^2+27x-27-x^3+27+9x^2+18x+1-15=0\)
\(\Leftrightarrow45x=14\)
\(\Leftrightarrow x=\frac{14}{45}\)
Giải các phương trình sau :
a, (x-1)³+(2-x)(4+2x+x²)+3x(x+2)=17
b,(x+2)(x²-2x+4)-x(x²-2)=15
c,(x-3)³-(x-3)(x²+3x+9)+9(x+1)²=15
d,x(x-5)(x+5)-(x+2)(x²-2x+4)=3
a) (x - 1)3 + (2 - x)(4 + 2x + x2) + 3x(x + 2) = 12
<=> x3 - 2x2 + x - x2 + 2x - 1 + 8 + 4x + 2x2 - 4x - 2x2 + 3x2 + 6x = 17
<=> 9x + 7 = 17
<=> 9x = 17 - 7
<=> 9x = 10
<=> x = \(\frac{10}{9}\)
b) (x + 2)(x2 - 2x + 4) - x(x2 - 2) = 15
<=> x3 - 2x2 + 4x + 2x2 - 4x + 8 - x3 + 2x = 15
<=> 2x + 8 = 15
<=> 2x = 15 - 8
<=> 2x = 7
<=> x = \(\frac{7}{2}\)
c) (x - 3)3 - (x - 3)(x2 + 3x + 9) + 9(x2 + 1)2 = 15
<=> x3 + 45x - 18 - x3 - 3x2 - 9x + 3x2 + 9x + 27 = 15
<=> 45x + 9 = 15
<=> 45x = 15 - 9
<=> 45x = 6
<=> x = \(\frac{6}{45}\)
d) x(x - 5)(x + 5) - (x + 2)(x2 - 2x + 4) = 3
<=> x3 - 25x - x3 + 2x2 - 4x - 8 = 3
<=> -25x - 8 = 3
<=> -25x = 3 + 8
<=> -25x = 11
<=> x = \(-\frac{11}{25}\)
a)\(\left(x-1\right)^3+\left(2-x\right)\left(4+2x+x^2\right)+3x\left(x+2\right)=17\)
\(=>x^3-3x^2+3x-1+8-x^3+3x^2+6x=17\)
\(=>9x+7=17=>9x=10=>x=\frac{10}{9}\)
Bạn đăng 1 lần 4 câu làm mik nản quá!
b)\(\left(x+2\right)\left(x^2-2x+4\right)-x\left(x^2-2\right)=15\)
\(=>x^3+8-x^3+2x=15=>2x+8=15=>2x=7=>x=\frac{7}{2}\)
tìm x biết:
(3x-1) [- 1/2x+5]=0
1/4+1/3:(2x-1)=-5
[2x+3/5]2 - 9/25=0
-5(x+1/5)-1/2(x-2/3)=3/2x - 5 /6
[x+1/2]x [2/3-2x]=0
17/2-|2x-3/4|=-7/4
2/3x-1/2x =5/12
(x+1/5)2+17/25=26/25
[x.44/7+3/7].11/5-3/7=-2
3[3x-1/2]+1/9=0
tìm x biết:
(3x-1) [- 1/2x+5]=0
1/4+1/3:(2x-1)=-5
[2x+3/5]2 - 9/25=0
-5(x+1/5)-1/2(x-2/3)=3/2x - 5 /6
[x+1/2]x [2/3-2x]=0
17/2-|2x-3/4|=-7/4
2/3x-1/2x =5/12
(x+1/5)2+17/25=26/25
[x.44/7+3/7].11/5-3/7=-2
3[3x-1/2]+1/9=0
Toán lớp 6Tìm x
Trả lời Câu hỏi tương tự
Chưa có ai trả lời câu hỏi này,bạn hãy là người đâu tiên giúp nguyenvanhoang giải bài toán này !
a,4x-10=0 b, 7-3x=9-x c, 2x-(3-5x) = 4(x+3)
d, 5-(6-x)=4(3-2x) e, 4(x+3)=-7x+17 f, 5(x-3) - 4=2(x-1)+7
g, 5(x-3)-4=2(x-1)+7 h,4(3x-2)-3(x-4)=7x+20
`a,4x-10=0 `
`<=> 4x=10`
`<=>x=10/4`
`<=>x=5/2`
`b, 7-3x=9-x `
`<=>-3x+x=9-7`
`<=>-2x=2`
`<=>x=-1`
`c, 2x-(3-5x) = 4(x+3)`
`<=>2x-3+5x=4x+12`
`<=>2x+5x-4x=12+3`
`<=>3x=15`
`<=>x=5`
`d, 5-(6-x)=4(3-2x) `
`<=>5-6+x=12-8x`
`<=>x+8x=12-5+6`
`<=>9x=13`
`<=>x=13/9`
`e, 4(x+3)=-7x+17 `
`<=>4x+12=-7x+17`
`<=>4x+7x=17-12`
`<=>11x=5`
`<=>x=5/11`
`f, 5(x-3) - 4=2(x-1)+7`
`<=>5x-15-4=2x-2+7`
`<=>5x-2x=15+4-2+7`
`<=>3x=24`
`<=>x=8`
`g, 5(x-3)-4=2(x-1)+7 `
`<=>5x-15-4=2x-2+7`
`<=>5x-2x=15+4-2+7`
`<=>3x=24`
`<=>x=8`
`h,4(3x-2)-3(x-4)=7x+20`
`<=>12x-8-3x+12=7x+20`
`<=>12x-3x-7x=20+8+12`
`<=>2x=40`
`<=>x=20`
tìm x
a) (x+2)(x+3)-(x-2)(x+5)=6
b) (3x+2)(2x+9)-(x+2)(6x+1)=(x+1)-(x-6)
c) 3(2x-1)(3x-1)-(2x-3)(9x-1)=0
a: Ta có: \(\left(x+2\right)\left(x+3\right)-\left(x-2\right)\left(x+5\right)=6\)
\(\Leftrightarrow x^2+5x+6-x^2-3x+10=6\)
\(\Leftrightarrow2x=-10\)
hay x=-5
b: Ta có: \(\left(3x+2\right)\left(2x+9\right)-\left(x+2\right)\left(6x+1\right)=\left(x+1\right)-\left(x-6\right)\)
\(\Leftrightarrow6x^2+27x+4x+18-6x^2-x-12x-2=x+1-x+6\)
\(\Leftrightarrow18x+16=7\)
hay \(x=-\dfrac{1}{2}\)
c: Ta có: \(3\left(2x-1\right)\left(3x-1\right)-\left(2x-3\right)\left(9x-1\right)=0\)
\(\Leftrightarrow3\left(6x^2-2x-3x+1\right)-\left(18x^2-2x-27x+3\right)=0\)
\(\Leftrightarrow18x^2-15x+3-18x^2+27x-3=0\)
hay x=0