Tìm x
\(1988< 5xX-2< 1998\)
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5.X/2-3=3/10.15
5.x/2-3=9/2
5.x/2=9/2+3
x/2=15/2:5
x=3/2.2
x=3
^^ungr hộ nha
19991999 . 1998 - 19981998.1999
= 1999 . 1001 . 1998 - 1998 . 1001 . 1999
= 0
tick nhé bạn
19991999 . 1998 - 19981998.1999
= 1999 . 1001 . 1998 - 1998 . 1001 . 1999
= 0
a)\(\frac{5}{9}\times x-1=\frac{8}{9}\)
\(\frac{5}{9}\times x=\frac{8}{9}+1\)
\(\frac{5}{9}\times x=\frac{17}{9}\)
\(x=\frac{17}{9}:\frac{5}{9}\)
\(x=\frac{17}{5}\)
a) 213 - 2 x X = 47
2 x X = 213 - 47
2 x X = 166
X = 166 : 2
X = 83
b) 3 x ( X + 1 ) - 300 = 906
3 x ( X + 1 ) = 906 + 300
3 x ( X + 1 ) = 1206
X + 1 = 1206 : 3
X + 1 = 402
X = 402 - 1
X = 401
c) \(\frac{7}{3}-\frac{2}{3}\times x=\frac{1}{4}\)
\(\frac{2}{3}\times x=\frac{7}{3}-\frac{1}{4}\)
\(\frac{2}{3}\times x=\frac{25}{12}\)
\(x=\frac{25}{12}:\frac{2}{3}\)
\(x=\frac{25}{8}\)
d) \(\frac{2}{5}\times x+\frac{7}{8}=2\)
\(\frac{2}{5}\times x=2-\frac{7}{8}\)
\(\frac{2}{5}\times x=\frac{9}{8}\)
\(x=\frac{9}{8}:\frac{2}{5}\)
\(x=\frac{45}{16}\)
Học tốt #
a) \(213-2\cdot x=47\)\(\Leftrightarrow2\cdot x=166\Leftrightarrow x=83\)
b)\(3x\left(x+1\right)-300=906\Leftrightarrow3x\left(x+1\right)=606\)
\(\Leftrightarrow x\left(x+1\right)=202\Leftrightarrow x^2+x-202=0\)
\(\Leftrightarrow\left(x+\frac{1}{2}\right)^2-202,25=0\)\(\Leftrightarrow\orbr{\begin{cases}x+\frac{1}{2}=\sqrt{202,25}\\x+\frac{1}{2}=-\sqrt{202,25}\end{cases}}\)
\(\Leftrightarrow\orbr{\begin{cases}x=\sqrt{202,25}-0,5\\x=-\sqrt{202,25}-0,5\end{cases}}\)
f) 11.(x+2)=5.x+40
=> 11x+22=5x+40
=> 6x=18
=> x=18:6=3
g)11.(x-6)=4.x+11
=> 11.x+(-66)=4x+11
=> 7x=77
=> x=77:7=11
h) (3x-4):x+10=12
=> 3x:x-4:x=12-10=2
=> 3-4:x=2
=> 4:x=3-2=1
=> x=4:1=4
k)(5x+7):x+20=26
=> 5x:x+7:x=26-20=6
=> 5+7:x=6
=> => 7:x=6-5=1
=> x=7:1=7
m) x.1999-x=1999.1997+1999
=> x.1998=1999.(1997+1)
=> x.1998=1999.1998
=> x=1999
**** cho mik nha Nguyễn Thị Thảo Ly
1988 < 5 x X - 2 < 1998
1988 < [ ( 1998 - 8 ) : 5 + 1 ] x 5 - 2 < 1998
1988 < ( 1990 : 5 + 1 ) x 5 - 2 < 1998
1988 < 399 x 5 - 2 < 1998
= > Vậy số cần tìm x = 399
1988 < 5 . x - 2 < 1998
1998 < { ( 1998 - 8 ) : 5 + 1 } . 5 - 2 < 1998
1988 < ( 1990 : 5 + 1 ) . 5 - 2 < 1998
1988 < ( 398 + 1 ) . 5 - 2 < 1998
1988 < 399 . 5 - 2 < 1998
=> x = 399
Vậy ...