tìm x
5^2.x+2^4.x=123
3^6:3^3+5.x=57
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2
12 tháng 6 2018
\(\left(\frac{3}{5}-x\right)+\frac{13}{20}=\frac{5}{6}\)
\(\frac{3}{5}-x=\frac{5}{6}-\frac{13}{20}\)
\(\frac{3}{5}-x=\frac{11}{60}\)
\(x=\frac{3}{5}-\frac{11}{60}\)
\(x=\frac{5}{12}\)
\(\left(x-\frac{1}{2}\right)\cdot\frac{5}{3}=\frac{7}{4}-\frac{1}{2}\)
\(\left(x-\frac{1}{2}\right)\cdot\frac{5}{3}=\frac{5}{4}\)
\(x-\frac{1}{2}=\frac{5}{4}:\frac{5}{3}\)
\(x-\frac{1}{2}=\frac{3}{4}\)
\(x=\frac{3}{4}+\frac{1}{2}\)
\(x=\frac{5}{4}\)
12 tháng 6 2018
( 3/5 - x ) + 13/20 = 5/6
3/5 - x = 5/6 - 13/20
3/5 - x = 89/60
x = 3/5 - 89/60
x = 25/12
( x - 1/2 ) x 5/3 = 7/4 - 1/2
( x - 1/2 ) x 5/3 = 5/4
x - 1/2 = 5/4 : 5/3
x - 1/2 = 35/12
x = 35/12 + 1/2
x = 41/12
NT
3
9 tháng 1 2021
a) Ta có: \(7-\left(2x+4\right)=-\left(x+4\right)\)
\(\Leftrightarrow7-2x-4=-x-4\)
\(\Leftrightarrow-2x+3+x+4=0\)
\(\Leftrightarrow-x+7=0\)
\(\Leftrightarrow-x=-7\)
hay x=7
Vậy: S={7}
b) Ta có: \(\dfrac{2+x}{5}-0.5x=\dfrac{1-2x}{4}+0.25\)
\(\Leftrightarrow\dfrac{4\left(2+x\right)}{20}-\dfrac{0.5x\cdot20}{20}=\dfrac{5\left(1-2x\right)}{20}+\dfrac{20\cdot0.25}{20}\)
\(\Leftrightarrow4\left(2+x\right)-10x=5\left(1-2x\right)+5\)
\(\Leftrightarrow8+4x-10x=5-10x+5\)
\(\Leftrightarrow-6x+8=-10x+10\)
\(\Leftrightarrow-6x+8+10x-10=0\)
\(\Leftrightarrow4x-2=0\)
\(\Leftrightarrow4x=2\)
hay \(x=\dfrac{1}{2}\)
Vậy: \(S=\left\{\dfrac{1}{2}\right\}\)
d) Ta có: \(\dfrac{x-1}{59}+\dfrac{x-2}{58}+\dfrac{x-3}{57}=\dfrac{x-59}{1}+\dfrac{x-58}{2}+\dfrac{x-57}{3}\)
\(\Leftrightarrow\dfrac{x-1}{59}-1+\dfrac{x-2}{58}-1+\dfrac{x-3}{57}-1=\dfrac{x-59}{1}-1+\dfrac{x-58}{2}-1+\dfrac{x-57}{3}-1\)
\(\Leftrightarrow\dfrac{x-60}{59}+\dfrac{x-60}{58}+\dfrac{x-60}{57}=\dfrac{x-60}{1}+\dfrac{x-60}{2}+\dfrac{x-60}{3}\)
\(\Leftrightarrow\left(x-60\right)\left(\dfrac{1}{59}+\dfrac{1}{58}+\dfrac{1}{57}\right)-\left(x-60\right)\left(1+\dfrac{1}{2}+\dfrac{1}{3}\right)=0\)
\(\Leftrightarrow\left(x-60\right)\left(\dfrac{1}{59}+\dfrac{1}{58}+\dfrac{1}{57}-1-\dfrac{1}{2}-\dfrac{1}{3}\right)=0\)
mà \(\dfrac{1}{59}+\dfrac{1}{58}+\dfrac{1}{57}-1-\dfrac{1}{2}-\dfrac{1}{3}\ne0\)
nên x-60=0
hay x=60
Vậy: S={60}
23 tháng 8 2018
1) = \(\frac{3}{5}\)
2) =\(\frac{6}{7}\)
3)\(\frac{9}{13}\)
4)\(\frac{4}{13}\)
1) 5^2 . x + 2^4 . x = 123
=> 25 .x + 16 .x = 123
=> x ( 25 + 16 ) = 123
=> x . 41 = 123
=> x = 123 : 41
=> x = 3
b, 3^6 : 3 ^ 3 + 5.x = 57
=> 3^3 + 5.x = 57
=> 27 + 5x = 57
=> 5x = 57 - 27
=> 5x = 30
=> x = 30 : 5
=> x = 6
Bạn tính theo cách a.b + a.c = a(b+c)