tìm x
a, 54+x-65+3=12
b,x-45+65=59
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2 . 53 . 27 + 6 . 9 . 87 - 3 . 18 . 40
= 2. 53 . 9 . 3 + 2. 3 .9 .87 - 3 .2 .9 .40
= 54.53+54.87-54.40
=54(53+87-40)
=54. 100=5400
12 . 25 + 29 . 25 + 59 . 25
= 25 . ( 12+29+59)
=25 . 90
=2250
43 . 37 + 93 . 43 + 57 . 61 + 69 . 57
= 43.(37+93)+57(61+69)
=43.130+57.130
=130.(43+57)
=130.100
=13 000
12 . 53 + 53 . 172 - 53
=53(12+172-1)
=53.184
=9752
35 . 54 + 35 . 58 + 65 . 75 + 65 . 45
=35(54+58)+65(75+45)
=35.112+65.120
=3920+7800
=11720
39 . 8 + 70 . 3 + 31 . 8
=8(39+31)+70.3
=8.70+70.3
=70.(8+3)
=70.11
=770
65+54-45.7356652245.0+456
=65+54+456
=575
_ht_
65 + 54 - 45 x 7356652245 x 0 +456
=575
\(\dfrac{x+1}{65}+\dfrac{x+3}{63}\) = \(\dfrac{x+5}{61}\) + \(\dfrac{x+7}{59}\)
<=> \(\dfrac{x+1}{65}+1+\dfrac{x+3}{63}+1\) = \(\dfrac{x+5}{61}\) + 1 + \(\dfrac{x+7}{59}\) + 1
<=> \(\dfrac{x+66}{65}+\dfrac{x+66}{63}\) = \(\dfrac{x+66}{61}\) + \(\dfrac{x+66}{59}\)
<=> \(\dfrac{x+66}{65}+\dfrac{x+66}{63}\) - \(\dfrac{x+66}{61}\) - \(\dfrac{x+66}{59}\) = 0
<=> (x + 66) . (\(\dfrac{1}{65}+\dfrac{1}{63}+\dfrac{1}{61}+\dfrac{1}{59}\)) = 0
<=> x + 66 = 0
<=> x = -66
1 + 1 = 2
5 x 3 = 15
7 x 4 = 28
65 + 45 = 110
9 x 54 = 486
1 + 1 = 2
5 x 3 = 15
7 x 4 = 28
65 + 45 = 110
9 x 54 = 486
a) 54 + x - 65 + 3 = 12
54 + x - 65 = 9
54 + x = 74
x = 74 - 54
x = 20
b) x - 45 + 65 = 59
x - 45 = -6
x = -6 + 45
x = 39
\(a,54+x-65+3=12\)
\(\Leftrightarrow54+x-\left(65-3\right)=12\)
\(\Leftrightarrow54+x-62=12\)
\(\Leftrightarrow54-x=12+62\)
\(\Leftrightarrow54-x=74\)
\(\Leftrightarrow x=54-74\)
\(\Leftrightarrow x=-20\)
\(b,x-45+65=59\)
\(\Leftrightarrow x-\left(45-65\right)=59\)
\(\Leftrightarrow x-\left(-20\right)\)
\(\Leftrightarrow x+20=59\)
\(\Leftrightarrow x=59-20\)
\(\Leftrightarrow x=39\)