Tìm x biết (3x/7+1):(-4)=-1/6
B3 : tìm x biết
a, x + 3/4 = 1/4
b, 2/3x - 3/7 = 1/7
c, 1 2/3x - 50%x = - 1 1/6
\(a,x+\frac{3}{4}=\frac{1}{4}\)
\(\Rightarrow x=\frac{1}{4}-\frac{3}{4}=-\frac{1}{2}\)
\(b,\frac{2}{3}x-\frac{3}{7}=\frac{1}{7}\)
\(\Rightarrow\frac{2}{3}x=\frac{1}{7}+\frac{3}{7}\)
\(\Rightarrow\frac{2}{3}x=\frac{4}{7}\)
\(\Rightarrow x=\frac{4}{7}:\frac{2}{3}=\frac{4}{7}\cdot\frac{3}{2}=\frac{6}{7}\)
\(c,1\frac{2}{3}x-50\%x=-1\frac{1}{6}\)
\(\Rightarrow\frac{5}{3}x-\frac{50}{100}x=-\frac{7}{6}\)
\(\Rightarrow\left[\frac{5}{3}-\frac{50}{100}\right]x=-\frac{7}{6}\)
\(\Rightarrow\left[\frac{5}{3}-\frac{1}{2}\right]x=-\frac{7}{6}\)
\(\Rightarrow\frac{7}{6}x=-\frac{7}{6}\Leftrightarrow x=-\frac{7}{6}:\frac{7}{6}=-\frac{7}{6}\cdot\frac{6}{7}=-1\)
a,x+\(\frac{3}{4}\)=\(\frac{1}{4}\)
=>x =\(\frac{1}{4}\)-\(\frac{3}{4}\)
=> x =\(\frac{-1}{2}\)
Vậy x=\(\frac{-1}{2}\)
b,\(\frac{2}{3}\)x-\(\frac{3}{7}\)=\(\frac{1}{7}\)
=>\(\frac{2}{3}\)x =\(\frac{1}{7}\)+\(\frac{3}{7}\)
=>\(\frac{2}{3}\)x =\(\frac{4}{7}\)
=> x =\(\frac{4}{7}\) :\(\frac{2}{3}\)
=> x =\(\frac{4}{7}\).\(\frac{3}{2}\)
=> x =\(\frac{6}{7}\)
Vậy x=\(\frac{6}{7}\)
c,\(\frac{12}{3}\)x-50%x =\(\frac{-11}{6}\)
=>\(\frac{12}{3}\)x-\(\frac{1}{2}\)x=\(\frac{-11}{6}\)
=>x(\(\frac{12}{3}\)-\(\frac{1}{2}\))=\(\frac{-11}{6}\)
=>x(\(\frac{24}{6}\)-\(\frac{3}{6}\))=\(\frac{-11}{6}\)
=>x\(\frac{21}{6}\) =\(\frac{-11}{6}\)
=>x =\(\frac{-11}{6}\):\(\frac{21}{6}\)
=>x =\(\frac{-11}{6}\).\(\frac{6}{21}\)
=>x =\(\frac{-11}{21}\)
Vậy x=\(\frac{-11}{21}\)
Ý c, mk tưởng 1 2/3 và -1 1/6 là phân số nên mk giải sai ý đó
BÀI GIẢI LẠI :
1\(\frac{2}{3}\)x-50%x=-1\(\frac{1}{6}\)
\(\frac{5}{3}\)x-\(\frac{1}{2}\)x=\(\frac{-7}{6}\)
x(\(\frac{5}{3}\)-\(\frac{1}{2}\))=\(\frac{-7}{6}\)
x\(\frac{7}{6}\) =\(\frac{-7}{6}\)
x =\(\frac{-7}{6}\):\(\frac{7}{6}\)
x =-1
Vậy x=-1
xl vì bài giải trước nha
Tìm x biết
a) (x+2).(x+3)-(x+1).(x+7)=6
b) (8x-3).(3x+2)(3x+2) - (4x+7).(x+4) = (2x+1).(5x-1) - 33
a) \(\left(x+2\right)\left(x+3\right)-\left(x+1\right)\left(x+7\right)=6\)
\(\Leftrightarrow x^2+5x+6-x^2-8x-7=6\)
\(\Leftrightarrow-3x=7\)
\(\Leftrightarrow x=-\frac{7}{3}\)
b) \(\left(8x-3\right)\left(3x+2\right)\left(3x+2\right)-\left(4x+7\right)\left(x+4\right)=\left(2x+1\right)\left(5x-1\right)-33\)
\(\Leftrightarrow\left(8x-3\right)\left(9x^2+12x+4\right)-4x^2-23x-28=10x^2+3x-1-33\)
\(\Leftrightarrow72x^3+69x^2-4x-12-14x^2-26x+6=0\)
\(\Leftrightarrow72x^3+55x^2-30x-6=0\)
Nghiệm vô tỉ: \(x_1=-1,078...\) ; \(x_2=0,476...\) ; \(x_3=-0,162...\)
a) (x + 2)(x + 3) - (x + 1)(x + 7) = 6
=> x(x + 3) + 2(x + 3) - x(x + 7) - 1(x + 7) = 6
=> x2 + 3x + 2x + 6 - x2 - 7x - x - 7 = 6
=> x2 + 5x + 6 - x2 - 7x - x - 7 = 6
=> (x2 - x2) + (5x - 7x - x) + (6 - 7) = 6
=> -3x - 1 = 6
=> -3x = 7
=> x = -7/3
b) (8x - 3)(3x + 2)(3x + 2) - (4x + 7)(x + 4) = (2x + 1)(5x - 1) - 33
=> (8x - 3)(9x2 + 12x + 4) - [4x(x + 4) + 7(x + 4)] = 2x(5x - 1) + 1(5x - 1) - 33
=> 8x(9x2 + 12x + 4) - 3(9x2 + 12x + 4) - (4x2 + 16x + 7x + 28) = 10x2 - 2x + 5x - 1 - 33
=> 72x3 + 96x2 + 32x - 27x2 - 36x - 12 - 4x2 - 16x - 7x - 28 - 10x2 + 2x - 5x + 1 + 33 = 0
=> 72x3 + (96x2 - 27x2 - 10x2 - 4x2) + (32x - 36x - 16x - 7x + 2x - 5x) + (-12 - 28 + 1 + 33) = 0
=> 72x3 + 55x2 - 30x - 6 = 0
=> x vô nghiệm
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
Tìm x biết: a) |3x-2|=7 b) |1/4 - 2x/3| = 7/6 c) |8-|x+3||=2
a) |3x-2|=7
=> 3x-2=7 hoặc 3x-2=-7
=> 3x=9 hoặc 3x=-5
=> x=3 hoặc x=\(-\dfrac{5}{3}\)
Tìm x biết:
a,2x(x+1)-3-2x=5
b,2x(3x+1)+(4-2x)=7\
c,(x-3)^3-(x-3)(x^2+3x+9)+6(x-1)^2=6
a)\(2x\left(x+1\right)-3-2x=5\)
\(\Leftrightarrow2x^2+2x-3-2x=5\)
\(\Leftrightarrow2x^2=8\)
\(\Leftrightarrow x^2=4=\left(-2\right)^2=2^2\)
\(\Rightarrow x=2;-2\)
b)\(2x\left(3x+1\right)+\left(4-2x\right)=7\)
\(\Leftrightarrow6x^2+2x+4-2x=7\)
\(\Leftrightarrow6x^2+4=7\)
\(\Leftrightarrow6x^2=3\)
\(\Leftrightarrow x^2=\frac{1}{2}=-\sqrt{\frac{1}{2}}=\sqrt{\frac{1}{2}}\)
c)\(\left(x-3\right)^3-\left(x-3\right)\left(x^2+3x+9\right)+6\left(x-1\right)^2=6\)
\(\Leftrightarrow x^3-9x^2+27x-27-x^3+27+6\left(x^2-2x+1\right)=6\)
\(\Leftrightarrow-3x^2+27x+6x^2-12x+6=6\)
\(\Leftrightarrow-3x^2+27x+6x^2-12x+6=6\)
\(\Leftrightarrow3x^2+15x=0\)
\(\Leftrightarrow3x\left(x+5\right)=0\)
\(\Rightarrow\orbr{\begin{cases}3x=0\\x+5=0\end{cases}\Rightarrow}\orbr{\begin{cases}x=0\\x=-5\end{cases}}\)
Tìm x biết:
a,2x(x+1)-3-2x=5
b.2x(3x+1)+(4-2x)=7
c,(x-3)^3-(x-3)(x^2+3x+9)+6(x-1)^2=6
tìm x biết :
a,(2x+ 4/5) (3x-1/2)= 0
b,(x-2/5) (x+4/7)= 0
c,-1 =|x- 5/6|= 1/2
d,x+ 5/8 x- 12/16x= 1
a. 2x+\(\dfrac{4}{5}\)=0 hoặc 3x-\(\dfrac{1}{2}\)=0
2x=- 4/5 hoặc 3x=1/2
x=-2/5 hoặc x=\(\dfrac{1}{6}\)
b. x-\(\dfrac{2}{5}\)=0 hoặc x+\(\dfrac{4}{7}\)=0
x=2/5 hoặc x=-\(\dfrac{4}{7}\)
d. x(1+5/8-12/16)=1
\(\dfrac{7}{8}\)x=1=> x=8/7
1/tính giá trị x+y biết x-3/y-5=3/5 và y-x=4
2/tìm x biết 15-x/7=x+7/4
3/tìm x,y,z biết 4/3x-2y=3/2z-4x=2/4y-3z và x+y-z=-10
4/tìm x,y,z biết x-1/2=y+3/4=z-5/6 và 5z-3x-4y=50
mấy bạn giúp mình nha mình cần gấp khoảng 1 giờ đã nộp bài gồi
1, tìm x biết:
a) 5x - 7( 2x - 5 ) < 2( x-1 )
b) 6 - 7( x - 4 ) lớn hơn hoặc bằng 3x + 2( 3- x )
c) 10x - 3( x - 5 )> 3x - 2( x - 4 )