a, (2x-3)2=16
b, (3x-2)5=-243
c, (x-7)x+1=(x-7)x+11
Tìm x biết :
a, 4.(18 - 5x) - 12.(3x - 7) = 15.(2x - 16) - 6(x + 14)
b, 5.(3x + 5) - 4.(2x - 3) = 5x + 3.(2x + 12) + 1
c, 2.(5x - 8) - 3.(4x - 5) = 4.(3x - 4) + 11
d, (3x + 2)(2x + 9) - (x + 2)(6x + 1) = (x + 1) - (x - 6)
e, (8x - 3)(3x + 2) - (4x + 7)(x + 4)= (2x + 1)(5x - 1) - 33
Noob ơi, bạn phải đưa vào máy tính ý solve cái là ra x luôn, chỉ tội là đợi hơi lâu
a, 4.(18 - 5x) - 12(3x - 7) = 15(2x - 16) - 6(x + 14)
=> 72 - 20x - 36x + 84 = 30x - 240 - 6x - 84
=> (72 + 84) + (-20x - 36x) = (30x - 6x) + (-240 - 84)
=> 156 - 56x = 24x - 324
=> 24x + 56x = 324 + 156
=> 80x = 480
=> x = 480 : 80 = 6
Vậy x = 6
b, 5(3x + 5) - 4(2x - 3) = 5x + 3(2x + 12) + 1
=> 15x + 25 - 8x + 12 = 5x + 6x + 36 + 1
=> (15x - 8x) + (25 + 12) = 11x + 37
=> 7x + 37 = 11x + 37
=> 11x - 7x = 0
=> x = 0
BT: Tìm x
a) 2x.(x-3)-x(2x+1)-3.(x+5)=11
b) x.(x-1)-(x^2+3x-5)-2.(x+3)=7
c) 5x.(x-7)-(5x+1).x-(x+3).2=13
d) (2x^2-3x+5)-2x.(x-3)+(x-1).(-2)=10
a) \(2x\left(x-3\right)-x\left(2x+1\right)-3\left(x+5\right)=11\)
\(\Rightarrow2x^2-6x-2x^2-x-3x-15=11\)
\(\Rightarrow-10x=26\Rightarrow x=-2,6\)
Vậy ...........
b) \(x\left(x-1\right)-\left(x^2+3x-5\right)-2\left(x+3\right)=17\)
\(\Rightarrow x^2-x-x^2-3x+5-2x-6=17\)
\(\Rightarrow-6x=18\Rightarrow x=-3\)
c) \(5x\left(x-7\right)-\left(5x+1\right)x-\left(x+3\right)2=13\)
\(\Rightarrow5x^2-35x-5x^2-x-2x-6=13\)
\(\Rightarrow-38x=19\Rightarrow x=-\frac{1}{2}\)
d) \(\left(2x^2-3x+5\right)-2x\left(x-3\right)+\left(x-1\right)\left(-2\right)=10\)
\(\Rightarrow2x^2-3x+5-2x^2+6x-2x+2=10\)
\(\Rightarrow x=3\)
Bài 1 : chứng minh rằng các biểu thức sau đây không phụ thuộc vào x a,A=(3x+7)(2x+3)-(2x+3)-(3x-5)(2x+11) b,B=(x^2-2)(x^2+x-1)-x(x^3+x^2-3x-2) Bài 2:Tìm x biết: a,6x(5x+3)+3x(1-10x)=7 b,(3x-3)(5-21x)+(7x+4)(9x-5)=44 c,(x+1)(x+2)(x+5)-x^2(x+8)=27 d,(2x-1)(3-x)+(x-2)(x+3)=(1-x)(x+2) Bài 3 Tính a,(2x+3)^3 b,(x-3y)^3 c.(x+4)(x^2-4x+16) d,(1/3x+2y)(1/9x^2-2/3xy+4y) e,(x-3y)(x2+3xy+9y^2)
\(1,A=\left(3x+7\right)\left(2x+3\right)-\left(2x+3\right)-\left(3x-5\right)\left(2x+11\right)\\ =6x^2+23x+21-2x-3-6x^2-23x+55\\ =73-2x\left(đề.sai\right)\\ B=x^4+x^3-x^2-2x^2-2x+2-x^4-x^3+3x^2+2x\\ =2\\ 2,\\ a,\Leftrightarrow30x^2+18x+3x-30x^2=7\\ \Leftrightarrow21x=7\Leftrightarrow x=\dfrac{1}{3}\\ b,\Leftrightarrow-63x^2+78x-15+63x^2+x-20=44\\ \Leftrightarrow79x=79\Leftrightarrow x=1\\ c,\Leftrightarrow\left(x+5\right)\left(x^2+3x+2\right)-x^3-8x^2=27\\ \Leftrightarrow x^3+3x^2+2x+5x^2+15x+10-x^3-8x^2=27\\ \Leftrightarrow17x=17\Leftrightarrow x=1\)
\(d,\Leftrightarrow7x-2x^2-3+x^2+x-6=-x^2-x+2\\ \Leftrightarrow9x=11\Leftrightarrow x=\dfrac{11}{9}\)
a. (3x-1)x(-1/2x+5)=0
b. 2/3x+1/2x=5/2:15/4
c. (x.44/7+3/7).11/5-3/7=-2
d. 1/3x+2/5(x-1)=0
a: \(\left(3x-1\right)\left(-\dfrac{1}{2}x+5\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}3x-1=0\\5-\dfrac{1}{2}x=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{1}{3}\\x=10\end{matrix}\right.\)
b: \(\dfrac{2}{3}x+\dfrac{1}{2}x=\dfrac{5}{2}:\dfrac{15}{4}=\dfrac{5}{2}\cdot\dfrac{4}{15}=\dfrac{20}{30}=\dfrac{2}{3}\)
=>7/6x=2/3
hay \(x=\dfrac{2}{3}:\dfrac{7}{6}=\dfrac{2}{3}\cdot\dfrac{6}{7}=\dfrac{12}{21}=\dfrac{4}{7}\)
c: \(\left(\dfrac{44}{7}x+\dfrac{3}{7}\right)\cdot\dfrac{11}{5}=-2+\dfrac{3}{7}=-\dfrac{11}{7}\)
\(\Leftrightarrow x\cdot\dfrac{44}{7}+\dfrac{3}{7}=\dfrac{-11}{7}:\dfrac{11}{5}=\dfrac{-5}{7}\)
\(\Leftrightarrow x\cdot\dfrac{44}{7}=-\dfrac{8}{7}\)
hay \(x=-\dfrac{8}{7}:\dfrac{44}{7}=-\dfrac{2}{11}\)
A) 1/4(x+3)=3-1/2(x+1)-1/3(x+2)
B) 3x-11/11-x/3=3x-5/7-5x-3/9
C) x-3/17(2x-1)=7/34(1-2x)+10x-3
a: \(\Leftrightarrow x\cdot\dfrac{1}{4}+\dfrac{3}{4}=3-\dfrac{1}{2}x-\dfrac{1}{2}-\dfrac{1}{3}x-\dfrac{2}{3}\)
=>13/12x=13/12
hay x=1
b: \(\Leftrightarrow\dfrac{3x-11}{11}-\dfrac{x}{3}=\dfrac{3x-5}{7}-\dfrac{5x-3}{9}\)
\(\Leftrightarrow\dfrac{3}{11}x-1-\dfrac{1}{3}x=\dfrac{3}{7}x-\dfrac{5}{7}-\dfrac{5}{9}x+\dfrac{1}{3}\)
\(\Leftrightarrow x\cdot\dfrac{46}{693}=\dfrac{13}{21}\)
hay x=429/46
tìm x
a,(3x^2-x+1)(x-1)+x^2(4-3x)=5/2
b,4(x+1)^2+(2x-1)^2-8(x-1)(x+1)=11
c,(2x-1)^2+(x+3)^2-5(x+7)(x-7)=0
a)
\(\left(3x^2-x+1\right)\left(x-1\right)+x^2\left(4-3x\right)=\frac{5}{2}\)
\(\Leftrightarrow3x^3-x^2+x-3x^2+x-1+4x^2-3x^3=\frac{5}{2}\)
\(\Leftrightarrow2x-1=\frac{5}{2}\Leftrightarrow2x=1+\frac{5}{2}=\frac{7}{2}\Leftrightarrow x=\frac{7}{4}\)
b)
\(4\left(x+1\right)^2+\left(2x-1\right)^2-8\left(x-1\right)\left(x+1\right)=11\)
\(\Leftrightarrow4\left(x^2+2x+1\right)+\left(4x^2-4x+1\right)-8\left(x^2-1\right)=11\)
\(\Leftrightarrow4x^2+8x+4+4x^2-4x+1-8x^2+8=11\)
\(\Leftrightarrow8x+4-4x+1+8=11\Leftrightarrow4x+13=11\Leftrightarrow4x=-2\Leftrightarrow x=-\frac{1}{2}\)
c)
\(\left(2x-1\right)^2+\left(x+3\right)^2-5\left(x+7\right)\left(x-7\right)=0\)
\(\Leftrightarrow4x^2-4x+1+x^2+6x+9-5\left(x^2-7^2\right)=0\)
\(\Leftrightarrow4x^2-4x+1+x^2+6x+9-5x^2+245=0\)
\(\Leftrightarrow-4x+1+6x+9+245=0\Leftrightarrow2x+255=0\Leftrightarrow x=-\frac{255}{2}\).
a ) ( 3x2 - x + 1 ) ( x + 1 ) + x2 ( 4 - 3x ) = 5/2
=> 3x3 + 3x2 - x2 - x + x + 1 + 4x2 - 3x3 = 5/2
=> 6x2 + 1 = 5/2
=> 6x2 = 1,5
=> x2 = 0,25
=> x = 0,5
a ) ( 3x 2 - x + 1 ) ( x + 1 ) + x 2 ( 4 - 3x ) = 5/2
=> 3x 3 + 3x 2 - x 2 - x + x + 1 + 4x 2 - 3x 3 = 5/2
=> 6x 2 + 1 = 5/2
=> 6x 2 = 1,5
=> x 2 = 0,25
=> x = 0,5
Bài 1:
a)-2x-3.( x-17 )= 34-2.( -x+25 )
b)17x+3.( -16x-37 )= 2x+43-4x
c){-3x+2. [ 45-x-3 ( 3x+7 ) -2x]+4x} = 55
g)-103-57: [ 5.( 2x-1 )2-( -9 )0 ]
Bài 2:
a)-5.( -x+7 )-3.( -x-5 )=-4.( 12-x )+48
b)7.( -x-7 )-4.( -2x-11 )=7.( 4x+10 )+9
c)-2.( 15-3x )-4.( -7x+8 )=-5-9.( -2x+1 )
d)5.( -3x-7 )-4.( -2x-11 )=7.( 4x+10 )+9
e)4( x-2 )2-13=( -3 )2.2-11.( -3 )
f)-52-( 2x-1 )3=( -13 ).( -3 )
Giúp tớ vs!!!
Bài 4: Chứng minh rằng giá trị của biểu thức sau không phụ thuộc vào X
a)A = 2 x(x-1)-x(2x+1)-(3-3x)
b)B=2x(x-3)-(2x-2)(x-2)
c)C=(3x-5)(2x+11)-(2x+3)(3x+7)
d)D=(2x+11)(3x-5)-(2x+3)(3x+7)
Bài4:
\(a,A=2x\left(x-1\right)-x\left(2x+1\right)-\left(3-3x\right)\\ =2x^2-2x-2x^2-x-3+3x\\ =-3\)
Vậy...(đpcm)
\(b,B=2x\left(x-3\right)-\left(2x-2\right)\left(x-2\right)\\ =2x^2-6x-2x^2+6x-4\\ =-4\)
Vậy...(đpcm)
\(c,C=\left(3x-5\right)\left(2x+11\right)-\left(2x+3\right)\left(3x+7\right)\\ =6x^2+23x-55-6x^2-23x-21\\ =-21\)
Vậy...(đpcm)
d,Câu d là câu c
\(A=2x\left(x-1\right)-x\left(2x+1\right)-\left(3-3x\right)\)
\(A=2x^2-2x-2x^2-x-3+3x\)
\(A=-3\)
\(B=2x\left(x-3\right)-\left(2x-2\right)\left(x-2\right)\)
\(B=2x^2-6x-2x^2+4x-2x+4x-4\)
\(B=-4\)
2) c/m các biểu thức sau không phụ thuộc vào biến số
a) A=3.(x-1)2-(x+1)2+2(x-3) (x+3)-(2x+3)2-(5-20x)+5x(x-7) (x+7)-x.(2x-1)2-(x3+4x2-246x)-175
b) B=-2x.(3x+2)2+(4x+1)2+2(x3+8x2+3x-2)-(5-x)+(5x-2)2-(6x+1)2+11(x-2) (x+2)-16(3-2x) cần gắp
a: Đặt \(C=3\left(x-1\right)^2-\left(x+1\right)^2+2\left(x-3\right)\left(x+3\right)-\left(2x+3\right)^2-\left(5-20x\right)\)
\(D=5x\left(x-7\right)\left(x+7\right)-x\left(2x-1\right)^2-\left(x^3+4x^2-246x\right)-175\)
Do đó: A=C+D
\(C=3\left(x-1\right)^2-\left(x+1\right)^2+2\left(x-3\right)\left(x+3\right)-\left(2x+3\right)^2-\left(5-20x\right)\)
\(=3x^2-6x+3-x^2-2x-1+2x^2-18-\left(4x^2+12x+9\right)-5+20x\)
\(=4x^2-8x-16-4x^2-12x-9-5+20x\)
\(=-30\)
\(D=5x\left(x-7\right)\left(x+7\right)-x\left(2x-1\right)^2-\left(x^3+4x^2-246x\right)-175\)
\(=5x\left(x^2-49\right)-x\left(4x^2-4x+1\right)-x^3-4x^2+246x-175\)
\(=5x^3-245x-4x^3+4x^2-x-x^3-4x^2+246x-175\)
=-175
A=C+D=-30-175=-205
b: Đặt \(E=-2x\left(3x+2\right)^2+\left(4x+1\right)^2+2\left(x^3+8x^2+3x-2\right)-\left(5-x\right)\)
\(F=\left(5x-2\right)^2-\left(6x+1\right)^2+11\left(x-2\right)\left(x+2\right)-16\left(3-2x\right)\)
Do đó: B=E+F
\(E=-2x\left(3x+2\right)^2+\left(4x+1\right)^2+2\left(x^3+8x^2+3x-2\right)-\left(5-x\right)\)
\(=-2x\left(9x^2+12x+4\right)+16x^2+8x+1+2x^3+16x^2+6x-4-5+x\)
\(=-18x^3-24x^2-8x+32x^2+14x+1-5+x\)
\(=-18x^3+8x^2+7x-4\)
\(F=\left(5x-2\right)^2-\left(6x+1\right)^2+11\left(x-2\right)\left(x+2\right)-16\left(3-2x\right)\)
\(=25x^2-20x+4-36x^2-12x-1+11x^2-44-48+32x\)
\(=-95\)
\(B=-18x^3+8x^2+7x-99\)