Giúp mk với :
4-(7-x)=x-(13-4)
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\(=\frac{7}{11}+\frac{52}{77}-\frac{24}{77}\)\(=\frac{7}{11}+\frac{4}{11}\)\(=1\)
a)(x+4).(y+3)=3
Th1: 3= -3 *(-1)
x+4 = -3 => x= -7
y +3 = -1 => y= -4
Th2: 3 = (-1) * (-3)
x+4 = -1 => x= -5
y+3 = -3 => y= -6
Th3: 3= 3*1
x+4 = 3 => x= -1
y + 3 = 1 => y= -2
Th4: 3= 1*3
x+4 = 1 => x= -3
y+3 = 3 => y= 0
Vậy nếu x= -7 thì y=-4
nếu x= -5 thì y =-6
nếu x= -1 thì y= -2
nếu x=-3 thì y = 0
b)(2x-5).(6y-7)
Đẳng thức này có kết quả ko bạn?
a) \(\frac{25}{9}-\frac{12}{13}x=\frac{7}{9}\)
=> \(\frac{12}{13}x=\frac{25}{9}-\frac{7}{9}=\frac{18}{9}=2\)
=> \(x=2:\frac{12}{13}=2\cdot\frac{13}{12}=\frac{13}{6}\)
b) \(x:\frac{13}{3}=-2,5\)
=> \(x:\frac{13}{3}=-\frac{5}{2}\)
=> \(x=\left(-\frac{5}{2}\right)\cdot\frac{13}{3}=-\frac{65}{6}\)
c) \(\frac{x}{3}-\frac{1}{4}=-\frac{5}{6}\)
=> \(\frac{4x-3}{12}=-\frac{10}{12}\)
=> 4x - 3 = -10
=> 4x = -10 + 3 = -7
=> x = -7/4
Bài 2 :
\(A=a\cdot\frac{1}{3}+a\cdot\frac{1}{4}-a\cdot\frac{1}{6}=a\left(\frac{1}{3}+\frac{1}{4}-\frac{1}{6}\right)=a\cdot\frac{5}{12}\)
Thay a = -3/5 vào biểu thức ta có : \(A=\left(-\frac{3}{5}\right)\cdot\frac{5}{12}=\frac{-3}{12}=\frac{-1}{4}\)
\(B=b\cdot\frac{5}{6}+b\cdot\frac{3}{4}-b\cdot\frac{1}{2}=b\left(\frac{5}{6}+\frac{3}{4}-\frac{1}{2}\right)=b\cdot\frac{13}{12}\)
Thay b = 12/13 vào ta được kết quả là 1
a ) \(\frac{25}{9}-\frac{12}{13}\cdot x=\frac{7}{9}\)
\(\Rightarrow\frac{12}{13}\cdot x=\frac{25}{9}-\frac{7}{9}=\frac{18}{9}=2\)
\(\Rightarrow x=2\div\frac{12}{13}=2\cdot\frac{13}{12}=\frac{13}{6}\)
Vậy ...
b ) \(x\div\frac{13}{3}=-\frac{5}{2}\)
\(\Rightarrow x\div\frac{13}{3}=-\frac{5}{2}\)
\(\Rightarrow x=\left(-\frac{5}{2}\right)\cdot\frac{13}{3}=-\frac{65}{6}\)
Vậy ..
c ) \(\frac{x}{3}-\frac{1}{4}=-\frac{5}{6}\)
\(\Rightarrow\frac{4x-3}{12}=-\frac{10}{12}\)
\(\Rightarrow4x-3=-10\)
\(\Rightarrow4x=-10+3=-7\)
\(\Rightarrow x=-\frac{7}{4}\)
Vậy ....
A = ( -4/5 + 4/3 ) + (-5/4 + 14/5) - 7/3
= 8/15 + 31/20 - 7/3
= 25/12 - 7/3
= -1/4
B = 8/3 x 2/5 x 3/8 x 10x 19/92
= 16/15 x 15/4 x 19/92
= 4x19/92
= 19/23
C = - \(\dfrac{5}{7}\) x \(\dfrac{2}{11}\) + \(\dfrac{-5}{7}\) x \(\dfrac{9}{14}\) + \(\dfrac{1}{57}\)
= - \(\dfrac{10}{77}\) - \(\dfrac{45}{98}\) + \(\dfrac{1}{57}\)
= - \(\dfrac{635}{1078}\) + \(\dfrac{1}{57}\)
= - \(\dfrac{36195}{61446}\) + \(\dfrac{1078}{61446}\)
= - \(\dfrac{35117}{61446}\)
a) \(\frac{14}{15}:\frac{9}{10}=x:\frac{3}{7}\Rightarrow\frac{28}{27}=x:\frac{3}{7}\Rightarrow x=\frac{4}{9}\)
b) \(\left(x-\frac{4}{7}\right)^3=343\Rightarrow\left(x-\frac{4}{7}\right)^3=7^3\Rightarrow x-\frac{4}{7}=7\Rightarrow x=\frac{53}{7}\)
c) \(x^5=x^3\Leftrightarrow\hept{\begin{cases}x=1\\x=0\end{cases}}\)
e) \(\left(x-1\right)^4=16\Leftrightarrow\orbr{\begin{cases}\left(x-1\right)^4=2^4\\\left(x-1\right)^4=\left(-2\right)^4\end{cases}}\)\(\Leftrightarrow\orbr{\begin{cases}x-1=2\\x-1=\left(-2\right)\end{cases}}\Leftrightarrow\orbr{\begin{cases}x=3\\x=-1\end{cases}}\)
a) -32 -4.(x-5) = 0
<=>4.(x-5)=-32
<=>x-5=(-32):4
<=>x+5=-8
<=>x=-8+5
<=>x=-3
Vậy x=-3
b) 13.(x-5)=-169
<=>x-5=(-169):13
<=>x-5=-13
<=>x=-13+5
<=>x=-8
vậy x=-8
c) (-2).x+5 = (-3).(-3)+8
<=>(-2).x+5=17
<=>(-2).x=17-5
<=>(-2).x=12
<=>x=12:(-2)
<=>x=-6
Vậy x=-6
d) (-8).x = (-10).(-2)-4
<=>(-8).x=16
<=>x=16:(-8)
<=>x=-2
vậy x=-2
e) (-9).x+3 = (-2).(-7)+16
<=>(-9).x+3=30
<=>(-9).x=30-3
<=>(-9).x=27
<=>x=27:(-9)
<=>x=-3
Vậy x=-3
a: =152,3+7,7+2021,19-2021,19
=160
b: =7/15*3/14*20/13
\(=\dfrac{7}{14}\cdot\dfrac{3}{15}\cdot\dfrac{20}{13}=\dfrac{1}{2}\cdot\dfrac{1}{5}\cdot\dfrac{20}{13}=\dfrac{2}{13}\)
c: \(=\dfrac{7}{4}\left(\dfrac{13}{12}-\dfrac{10}{12}\right)+\dfrac{5}{6}=\dfrac{7}{16}+\dfrac{5}{6}=\dfrac{61}{48}\)
4-(7-x)=x-(13-4)
\(\Rightarrow4-7+x=x-13+4\)
\(\Rightarrow-3+x=x-17\)
\(\Rightarrow x\in\varnothing\)
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