tìm x biết 100-7.(x-5)=65
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IL
2
31 tháng 10 2015
(x-100)/24 + (x-98)/26 + (x-96)/28 = 3
<=> (x - 100)/24 -1 + (x-98)/26-1 (x-96)/28 -1 = 0
<=>(x-124)/24 + (x-124)/26 + (x - 124)/28 =0
<=>(x - 124) (1/24+1/26+1/28) = 0
vì 1/24+1/26+1/28 khác 0
=> x - 124 = 0
=> x = 124
2) (x-1)/65 + (x-3)/63 = (x-5)/61 + (x-7)/59
tương tự:
(x-1)/65 -1 +(x -3)/63 -1 = (x-5)/61-1 + (x-7)/59 -1
rút gọn được:
(x - 66).(1/65 + 1/63) = (x -66).(1/61 + 1/59)
(x - 66).(1/65 + 1/63 - 1/61 -1/59) = 0
=> x = 66 (lý luận tương tự câu trên)
19 tháng 7 2015
12.(x-3):3=64+8
12.(x-3):3=72
12.(x-3) =72.3
12.(x-3) =216
x-3 =216:12
x-3 =18
x =18+3
x =21
2 tháng 10 2016
100-7.(x-5)=65
7.(x-5)=100-65
7.(x-5)=35
x-5=35:7
x-5=5
x =5+5
x =10
Vậy x = 10
11 tháng 8 2018
\(1) 420+65.4=(x+175):5+30\)
\(\implies 420+260=(x+175):5+30\)
\(\implies 680=(x+175):5+30\)
\(\implies 650=(x+175):5\)
\(\implies 650.5-175=x\)
\(\implies 3075=x\)
\(2)x-4867=(175.2050.70):25+23\)
\(\implies x-4867=1004500+23\)
\(\implies x-4867=1004523\)
\(\implies x=1009390\)
\(3) 134-[(96-7x):4-2]=126\)
\(\implies (96-7x):4-2=8\)
\(\implies(96-7x):4=10\)
\(\implies 96-7x=40\)
\(\implies 7x=56\)
\(\implies x=8\)
\(4) 4-\{100-[(100-5x):8-5]:10\}:25=0\)
\(\implies 4-\{100-[(100-5x):8-5]:10\}=0\)
\(\implies 100-[(100-5x):8-5]:10=4\)
\(\implies 100-[(100-5x):8-5]=40\)
\(\implies (100-5x):8-5=60\)
\(\implies (100-5x):8=65\)
\(\implies 100-5x=520\)
\(\implies 5x=-420\)
\(\implies x=-84\)
~ Hok tốt a~
.
TN
13 tháng 7 2016
\(\Rightarrow\frac{x-1}{65}-1+\frac{x-3}{63}-1=\frac{x-5}{61}-1+\frac{x-7}{59}-1\)
\(\Rightarrow\frac{x-66}{65}+\frac{x-66}{63}=\frac{x-66}{61}+\frac{x-66}{59}\)
\(\Rightarrow\frac{x-66}{65}+\frac{x-66}{63}-\frac{x-66}{61}-\frac{x-66}{59}=0\)
\(\Rightarrow x-66=0\).Do\(\frac{x-66}{65}+\frac{x-66}{63}-\frac{x-66}{61}-\frac{x-66}{59}\ne0\)
\(\Rightarrow x=66\)
9 tháng 4 2019
\(a,\frac{x+1}{65}+\frac{x+2}{64}=\frac{x+3}{63}+\frac{x+4}{62}\)
\(\Rightarrow\left[\frac{x+1}{65}+1\right]+\left[\frac{x+2}{64}+1\right]=\left[\frac{x+3}{63}+1\right]+\left[\frac{x+4}{62}+1\right]\)
\(\Rightarrow\frac{x+1+65}{65}+\frac{x+2+64}{64}=\frac{x+3+63}{63}+\frac{x+4+62}{62}\)
\(\Rightarrow\frac{x+66}{65}+\frac{x+66}{64}=\frac{x+66}{63}+\frac{x+66}{62}\)
\(\Rightarrow\frac{x+66}{65}+\frac{x+66}{64}=\frac{x+66}{63}+\frac{x+66}{62}=0\)
\(\Rightarrow\left[x+66\right]\left[\frac{1}{65}+\frac{1}{64}-\frac{1}{63}+\frac{1}{62}\right]=0\)
Mà \(\frac{1}{65}+\frac{1}{64}-\frac{1}{63}+\frac{1}{62}\ne0\)
\(\Rightarrow x+66=0\)
\(\Rightarrow x=0-66=-66\)
Auto làm nốt câu b
AN
9 tháng 4 2019
a, Cộng cả 2 vế với 2
Ta có \(\frac{x+1}{64}+\frac{x+2}{63}+2=\frac{x+3}{62}+\frac{x+4}{61}+2\)
\(\left(\frac{x+1}{64}+\frac{64}{64}\right)+\left(\frac{x+2}{63}+\frac{63}{63}\right)=\left(\frac{x+3}{62}+\frac{62}{62}\right)+\left(\frac{x+4}{61}+\frac{61}{61}\right)\)
=> \(\frac{x+65}{64}+\frac{x+65}{63}=\frac{x+65}{62}+\frac{x+65}{61}\)\(\)
=> \(\frac{x+65}{64}+\frac{x+65}{63}-\frac{x+65}{62}-\frac{x+65}{61}=0\)
=> \(\left(x+65\right)\left(\frac{1}{64}+\frac{1}{63}-\frac{1}{62}-\frac{1}{61}\right)=0\)
Do \(\frac{1}{64}+\frac{1}{63}-\frac{1}{62}-\frac{1}{61}\ne0\)=> \(x+65=0\)
=> \(x=-65\)
b , Lm tương tự như Câu a
Chúc bn hok tốt
LM
7 tháng 12 2017
\(\frac{x+1}{65}+\frac{x+3}{63}=\frac{x+5}{61}+\frac{x+7}{59}\)
\(\Leftrightarrow\frac{\left(x+1\right)}{65}-1+\frac{\left(x+3\right)}{63}-1=\frac{\left(x+5\right)}{61}-1+\frac{\left(x+7\right)}{59}\)
\(\Leftrightarrow\left(x-66\right).\left(\frac{1}{65}+\frac{1}{63}\right)=\left(x-66\right).\left(\frac{1}{61}+\frac{1}{59}\right)\)
\(\Leftrightarrow\left(x-66\right).\left(\frac{1}{65}+\frac{1}{63}-\frac{1}{61}-\frac{1}{59}\right)=0\)
\(\Rightarrow x=66\)
KK
5 tháng 1 2019
\(\frac{x+1}{65}+\frac{x+3}{63}=\frac{x+5}{61}+\frac{x+7}{59}\)
=> \(\left(\frac{x+1}{65}+1\right)+\left(\frac{x+3}{63}+1\right)=\left(\frac{x+5}{61}+1\right)+\left(\frac{x+7}{59}+1\right)\)
=> \(\frac{x+66}{65}+\frac{x+66}{63}=\frac{x+66}{61}+\frac{x+66}{59}\)
=> \(\left(x+66\right).\left(\frac{1}{65}+\frac{1}{63}-\frac{1}{61}-\frac{1}{59}\right)=0\)
=> x + 66 = 0
=> x = 0 - 66
=> x = -66
100-7.(x-5)=65
7.(x-5)=100-35
7.(x-5)=35
x-5=35:7
x-5=5
x=5+5
x=10