Tìm x, biết:
a, 32x+2=92x+3
b, (x-2016)5=(x-2016)7
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\(a,2448:\left[119-\left(x-6\right)\right]=24\)
\(119-\left(x-6\right)=2448:24\)
\(119-\left(x-6\right)=102\)
\(x-6=119-102\)
\(x-6=17\)
\(x=17+6\)
\(\Rightarrow x=23\)
\(b,2016-100\times\left(x+11\right)=128:8\)
\(2016-100\times\left(x+11\right)=16\)
\(100\times\left(x+11\right)=2016-16\)
\(100\times\left(x+11\right)=2000\)
\(x+11=2000:100\)
\(x+11=20\)
\(x=20-11\)
\(\Rightarrow x=9\)
\(a,2448:\left[119-\left(x-6\right)\right]=24\\ 119-\left(x-6\right)=2448:24\\ 119-\left(x-6\right)=102\\ x-6=119-102\\ x-6=17\\ x=17+6\\ x=23\\ b,2016-100\times\left(x+11\right)=128:8\\ 2016-100\times\left(x+11\right)=16\\ 100\times\left(x+11\right)=2016-16\\ 100\times\left(x+11\right)=2000\\ x+11=2000:100\\ x+11=20\\ x=20-11\\ x=9\)
a) \(\Rightarrow x=2021-2006=15\)
b) \(\Rightarrow2x-2016=64\Rightarrow2x=2016+64=2080\Rightarrow x=1040\)
c) \(\Rightarrow\left(2x+1\right)^3=81:3=27\Rightarrow2x+1=3\)
\(\Rightarrow2x=3-1=2\Rightarrow x=1\)
a.
31,5 – x = (18,6 – 12,3) : 3
31,5 - x = 2,1
x = 31,5 - 2,1
x = 29,4
b.
???
Lời giải:
a. Áp dụng TCDTSBN:
\(\frac{x}{y}=\frac{2}{5}\Rightarrow \frac{x}{2}=\frac{y}{5}=\frac{2x}{4}=\frac{y}{5}=\frac{2x-y}{4-5}=\frac{3}{-1}=-3\)
$\Rightarrow x=-3.2=-6; y=-3.5=-15$
b. Áp dụng TCDTSBN:
$\frac{x}{2}=\frac{y}{3}; \frac{y}{4}=\frac{z}{7}$
$\Rightarrow \frac{x}{8}=\frac{y}{12}=\frac{z}{21}$
$=\frac{2x}{16}=\frac{y}{12}=\frac{z}{21}=\frac{2x-y+z}{16-12+21}=\frac{50}{25}=2$
$\Rightarrow x=8.2=16; y=2.12=24; z=2.21=42$
c.
$\frac{x}{2}=\frac{y}{3}=\frac{z}{4}$
$\Rightarrow \frac{x^2}{4}=\frac{y^2}{9}=\frac{z^2}{16}=\frac{2z^2}{32}$
$=\frac{x^2-y^2+2z^2}{4-9+32}=\frac{108}{27}=4$
$\Rightarrow x^2=4.4=16; y^2=9.4=36; z^2=4.4=16$
Kết hợp với đkxđ suy ra:
$(x,y,z)=(4,6,4); (-4; -6; -4)$
a)15.x+15.2,7=105
15.(x+2,7)=105
x+2,7=7
x=7-2,7
x=4,3
Vậy x=4,3
b)x:7=920699:70
x:7=920699:10:7
x:7=92069,9:7
x=92069,9
Vậy x=92069,9
c)5.x-1952=2500-1947
5.x-1952=553
5.x=2505
x=501
Vậy x=501
d)x.2016-x=2016.2017+2016
x.(2016-1)=2016.(2017+1)
x.2015=2016.2018
x=\(\frac{2016.2018}{2015}\)
Vậy x\(\frac{2016.2018}{2015}\)
15.x+15.2,7=105
<=> 15.( x + 2,7 ) = 105
=> x + 2,7 = 7
=> x = 7 - 2,7
=> x = 4,3
x:7=920699:70
<=> x . 70 = 920699 . 7
=> x . 70 = 6444893
=> x = 6444893 : 70
=> x = 92069,9
5.x-1952=2500-1947
=> 5x - 1952 = 553
=> 5x = 553 + 1952
=> 5x = 2505
=> x = 2505 : 5
=> x = 501
x.2016-x=2016.2017+2016
=> x ( 2016 - 1 ) = 2016 ( 2017 + 1)
=> x . 2015 = 2016 . 2018
=> x : 2018 = 2016 : 2015
=> x : 2018 = \(\frac{2016}{2015}\)
=> x = \(\frac{2016}{2015}.2018\approx2019\)