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\(\frac{-x}{4}=\frac{-9}{x}\)
\(\Rightarrow-x\cdot x=-9\cdot4\)
\(\Rightarrow-x^2=-36\)
\(\Rightarrow-x^2=-6^2\)
\(\Rightarrow-x=-6\)
\(\Rightarrow\) \(x=6\)
\(\frac{x-1}{9}=\frac{8}{3}\)
\(\Rightarrow\left(x-1\right)\cdot3=9\cdot8\)
\(\Rightarrow\) \(3x-3=72\)
\(\Rightarrow\) \(3x=72+3\)
\(\Rightarrow\) \(3x=75\)
\(\Rightarrow\) \(x=75\div3\)
\(\Rightarrow\) \(x=25\)
457+218+143=(457+143)+218=600+218=818
b/ 346 + 412 + 188=346+(412+188)=346+600=946
\(c,\dfrac{8}{9}+\dfrac{14}{27}+\dfrac{1}{9}=\left(\dfrac{8}{9}+\dfrac{1}{9}\right)+\dfrac{14}{27}=1+\dfrac{14}{27}=\dfrac{41}{27}\)
d,\(\dfrac{1}{2}+\dfrac{3}{4}+\dfrac{1}{2}=\left(\dfrac{1}{2}+\dfrac{1}{2}\right)+\dfrac{3}{4}=1+\dfrac{3}{4}=\dfrac{7}{4}\)e,3,17.8,9+8,9.6,83=8,9(3,17+6,83=8,9.10=89
a)
457 + 218 + 143
= (457 + 143) + 218
= 600 + 218
= 818
b)
346 + 412 + 188
=346 + (412 + 188)
=346 + 600
= 946
c)
\(\dfrac{8}{9}+\dfrac{14}{27}+\dfrac{1}{9}=\left(\dfrac{8}{9}+\dfrac{1}{9}\right)+\dfrac{14}{27}=1+\dfrac{14}{27}=\dfrac{27}{27}+\dfrac{14}{27}=\dfrac{41}{27}.\)
d)
\(\dfrac{1}{2}+\dfrac{3}{4}+\dfrac{1}{2}=\left(\dfrac{1}{2}+\dfrac{1}{2}\right)+\dfrac{3}{4}=1+\dfrac{3}{4}=\dfrac{4}{4}+\dfrac{3}{4}=\dfrac{7}{4}.\)
e)\(\)
3,17 x 8,9 + 8,9 x 6,83 = 8,9 x ( 3,17 + 6,83 )
= 8,9 x 10
= 89
f)
1+3+5+...+19
= (19+1)+(17+3)+(15+5)+(13+7)+(11+9)
= 20+20+20+20+20
= 20 x 5
= 100
a)x-5/7=-2/3+1/3
x-5/7=-1/3
x=-1/3+5/7
x=8/21
b)1/3x+5/7=-9/4
x+5/7=-9/4:1/3
x+5/7=-27/4
x=-27/4-5/7
x=-209/28
a: x-5/7=-2/3+1/3
=>x-5/7=-1/3
=>x=-1/3+5/7=8/21
b: 1/3*x+5/7=-9/4
=>x*1/3=-9/4-5/7=-83/28
=>x=-83/28:1/3=-83/28*3=-249/28
c: 1/6x:1/4=-1/24
=>1/6x=-1/96
=>x=-1/16
tìm X nha
Anh k hiểu phần a) nên làm phần b) thôi nha
b) \(x+\frac{8}{14}=\frac{22}{14}\)
\(x=\frac{22}{14}-\frac{8}{14}\)
\(x=\frac{14}{14}=1\)
Vậy x = 1