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\(15x-9x+2x=72\)
\(\Rightarrow x\left(15-9+2\right)=72\)
\(\Rightarrow x.8=72\)
\(\Rightarrow x=72:8\)
\(\Rightarrow x=9\)
a,\(96-3x+1=42\)
<=> 97-3x=42
<=> 3x=55
<=>x=\(\frac{55}{3}\)
vậy.......
b, 15x-9x+2x=72
<=>8x=72
<=>x=9
vậy.....
c,\(3^{x+2}+3^x=10\)
\(\Leftrightarrow3^x\left(3^2+1\right)=10\)
\(\Leftrightarrow3^x=1\)
\(\Leftrightarrow x=0\)
vậy........
a 96 - 3 . x +1 = 42
96-3.x= 42-1
96 - 3 . x = 41
3.x= 96-41
3.x= 55
x= 55 : 3
x= \(\frac{55}{3}\)
b, 15x - 9x + 2x = 72
x.( 15-9+2) = 72
x8=72
x=72:8
x=9
c, 3x+2 + 3x = 10
\(\Rightarrow3^x.9+3^x=10\)
\(\Rightarrow3^x.10=10\)
\(\Rightarrow3^x=1\)
\(\Rightarrow x=0\)
a, => x-2x = 15+25
=> -x=40
=> x=-40
b, => -5x^2+50x = -3x-30x = -33x
=> 5x^2-50x=33x
=> 5x^2-50x-33x=0
=> 5x^2-83x=0
=> x.(5x-83) = 0
=> x=0 hoặc 5x-83=0
=> x=0 hoặc x=83/5
Tk mk nha
a)4.(x+3)-(2x-12)=x-(-11+4)
4x+12-2x+12=x+11-4
2x+24=x+7
2x-x=-24+7
x=-17
b)-(4x-13)+(5x-4)=-3-(-15+7)
-4x+13+5x-4=-3+15-7
(-4x+5x)+13-4=12-7
x+9=5
x=-4
c)(5x-3)-(-2x+4)=6x-12
5x-3+2x-4=6x-12
5x+2x-6x=3+4-12
x=-5
d)(15x+20)-(9x-3)=5x-(-12)
15x+20-9x+3=5x+12
15x-9x-5x=-20-3+12
x=-11
e,(7x+14)+(3x-8)=-(-9x+3)
7x+14+3x-8=9x-3
7x+3x-9x=-14+8-3
x=-9
a)
\(512-\left(128-5x\right)=3x+12\\ 512-128+5x=3x+12\\ 384+5x=3x+12\\ 5x-3x=12-384\\ 2x=-372\\ x=\left(-372\right):2\\ x=-186\)
b)
\(\left(2x-1\right)+\left(4x-2\right)+...+\left(400x-200\right)=5+10+...+1000\\ \left(2x+4x+...+400x\right)-\left(1+2+...+200\right)=5+10+...+1000\\ x\left(2+4+...+400\right)=\left(5+10+...+1000\right)+\left(1+2+...+200\right)\\ 2x\cdot\left(1+2+...+200\right)=5\cdot\left(1+2+...+200\right)+1\cdot\left(1+2+...+200\right)\\ 2x\cdot\left(1+2+...+200\right)=\left(5+1\right)\cdot\left(1+2+...+200\right)\\ 2x\cdot\left(1+2+...+200\right)=6\cdot\left(1+2+...+200\right)\\ \Rightarrow2x=6\\ x=6:2\\ x=3\)
c)
\(\left(x+2\right)+\left(4x+4\right)+\left(7x+6\right)+...+\left(25x+18\right)+\left(28x+20\right)=1560\\ \left(x+4x+7x+...+25x+28x\right)+\left(2+4+6+...+18+20\right)=1560\\ x\left(1+4+7+...+25+28\right)+110=1560\\ 145x+110=1560\\ 145x=1560-110\\ 145x=1450\\ x=1450:145\\ x=10\)
d)
\(x+4x+5x+9x+14x+...+97x=500\\ x\left(1+4+5+9+14+...+97\right)=500\)
Dãy số trong ngoặc có quy luật: Số thứ \(n\) bằng số thứ \(n-1\) cộng số thứ \(n-2\)
Suy ra dãy số đó là: \(1+4+5+9+14+23+37+60+97=250\)
Thế vào ta được:
\(250x=500\\ x=500:250\\ x=2\)
e)
\(720-\left[41-\left(2x-5\right)\right]=2^3\cdot5\\ 720-41+\left(2x-5\right)=8\cdot5\\ 720-41+2x-5=40\\ \left(720-41-5\right)+2x=40\\ 674+2x=40\\ 2x=40-674\\ 2x=-634\\ x=\left(-634\right):2\\ x=-317\)
f)
\(697:\dfrac{15x+364}{x}=17\\ \dfrac{15x+364}{x}=697:17\\ \dfrac{15x+364}{x}=41\\ \dfrac{15x+364}{x}\cdot x=41x\\ 15x+364=41x\\ 364=41x-15x\\ 364=26x\\ x=364:26\\ x=14\)
a) 4x + 3x = 217
x( 4 + 3 ) = 217
7x = 217
x = 217 : 7 = 31
Vậy x = 31
b) 9x - 3x = 216
( 9 -3)x = 216
6x = 216
x = 216:6 = 36
Vậy x = 36
c) 6x - 3x + 23 = 230
( 6 - 3 )x = 230 - 23
3x = 207
x = 207 : 3 = 69
Vậy x = 69
d) 5x + 3x + x = 72
5x + 3x + 1x = 72
( 5 + 3 + 1 )x = 72
9x = 72
x = 72 : 9 = 8
Vậy x = 8
Chúc bạn học tốt nhé
a) \(4x+3x=217\)
\(\Rightarrow x\cdot\left(3+4\right)=217\)
\(\Rightarrow7x=217\)
\(\Rightarrow x=\dfrac{217}{7}\)
\(\Rightarrow x=31\)
b) \(9x-3x=216\)
\(\Rightarrow x\cdot\left(9-3\right)=216\)
\(\Rightarrow6x=216\)
\(\Rightarrow x=\dfrac{216}{6}\)
\(\Rightarrow x=36\)
c) \(6x-3x+23=230\)
\(\Rightarrow x\cdot\left(6-3\right)=230-23\)
\(\Rightarrow3x=207\)
\(\Rightarrow x=\dfrac{207}{3}\)
\(\Rightarrow x=69\)
d) \(5x+3x+x=72\)
\(\Rightarrow x\cdot\left(5+3+1\right)=72\)
\(\Rightarrow9x=72\)
\(\Rightarrow x=\dfrac{72}{9}\)
\(\Rightarrow x=8\)
1
a, 4x - 3x + 1 = 5
x =5-1
x =4
Vậy x=4
b, (2x - 4 ) . 3x =0
=> 2x - 4 =0 hoặc 3x = 0
=> 2x =4 hoặc x=0
=> x =2 hoặc x=0
vậy x= 2 hoặc x=0
c, x . ( x -1 ) - ( x-1 )=0
(x-1) . (x-1 ) =0
(x-1)2 =02
x-1 =0
x =1
vậy x=1
2/ a, 7 . (x - 1 ) = 6x + 3
7x -7 = 6x +3
7x - 6x =7+3
x =10
vậy x=10
b, 8 . ( 2x - 3 ) -15x =4
16x - 24 -15x =4
16x - 15x =4+24
x =28
vậy x=28
c, 7 . 10 + ( x-1 ) .2 =100
70 + 2x -2 =100
2x -2 =100-70
2x -2 =30
2x =30+2
2x =32
x =16
vậy x=16
chúc bn học tốt
a)15x-9x+2x=72
(15x-9x)+2x=72
6x+2x=72
8x =72
x=72:8
x=9
Vậy x= 9
b)\(3^{x+2}+3^x=10\)
\(3^x.3^2+3^x=10\)
\(3^x.\left(3^2+1\right)=10\)
\(3^x.10=10\)
\(3^x=10:10\)
\(3^x=1\)
\(3^x=3^0\)
\(x=0\)
Vậy x=o