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-5/9 - ( -5/12 ) =-5/9+5/12=-20/36+15/36=-5/36
-1/16 - 1/15=-15/240-16/240=-31/240
11/36 - ( -7/24 )=11/36+7/24=22/72+21/72 =43/72
\(-\frac{5}{9}-\left(-\frac{5}{12}\right)=-\frac{60}{108}-\left(-\frac{45}{108}\right)=-\frac{15}{108}=-\frac{5}{36}.\)
\(\frac{-1}{6}-\frac{1}{15}=\frac{-5}{30}-\frac{2}{30}=\frac{-7}{30}\)
\(\frac{11}{36}-\left(-\frac{7}{24}\right)=\frac{22}{72}-\left(-\frac{21}{72}\right)=\frac{43}{72}\)
a) \(3\left(x-5\right)+6=36\)
\(\Rightarrow3\cdot\left(x-5\right)=36-6\)
\(\Rightarrow3\cdot\left(x-5\right)=30\)
\(\Rightarrow x-5=10\)
\(\Rightarrow x=10+5\)
\(\Rightarrow x=15\)
b) \(200-8\cdot\left(x+7\right)=24\)
\(\Rightarrow8\cdot\left(x+7\right)=200-24\)
\(\Rightarrow8\cdot\left(x+7\right)=176\)
\(\Rightarrow x+7=\dfrac{176}{8}\)
\(\Rightarrow x+7=22\)
\(\Rightarrow x=22-7\)
\(\Rightarrow x=15\)
c) \(\left(x-890\right)\left(74-x\right)=0\)
+) \(x-890=0\)
\(\Rightarrow x=890\)
+) \(74-x=0\)
\(\Rightarrow x=74\)
d) \(\left(31-x\right)\cdot\left(x-64\right)=0\)
+) \(31-x=0\)
\(\Rightarrow x=31\)
+) \(x-64=0\)
\(\Rightarrow x=64\)
\(3\left(x+3\right)=-24\)
\(x+3=-\dfrac{24}{3}\)
\(x+3=-8\)
\(x=-8-3\)
\(x=-11\)
24 chia hết cho 2x-1
=> 2x-1 \(\in\) Ư(24)
=> 2x-1 \(\in\) {1,2,3,4,6,8,12,24,-1,-2,-3,-4,-6,-8,-12,-24}
=> 2x \(\in\) { 2; 3;4;5;7;9;13;25;0;-1;-2;-3;-5;-7;-11;-23}
=> x \(\in\) {1;\(\dfrac{3}{2}\); 2; \(\dfrac{5}{2}\); \(\dfrac{7}{2}\);\(\dfrac{9}{2}\); \(\dfrac{13}{2}\); \(\dfrac{25}{2}\); 0;\(\dfrac{-1}{2}\); -1; \(\dfrac{-3}{2}\); \(\dfrac{-5}{2}\); \(\dfrac{-7}{2}\); \(\dfrac{-11}{2}\); \(\dfrac{-23}{2}\)}
Vậy...
<=> 46-x+11=-48
<=> x= 46+11+48
<=>x= 105
Vậy x=105
Chúc bạn học tốt nha!
a) 12 + 15 + 18 + ... + 90 ( 72 số hạng)
= (12 + 90 ) x 72 : 2
= 3672
b) 8 + 12 + 16 + ... + 100 ( 64 số hạng)
= (8 + 12 ) x 64 : 2
=640
c) 7 + 11 + 15 + ... + 43 + 47 (14 số hạng )
= (7 + 47 ) x 14 : 2
= 378
d) 1 + 6 + 11 + ........ + 46 + 51 (33 số hạng)
= (1 + 51 ) x 33 : 2
= 858
Công thức tính dãy số có quy luật :
lấy số đầu cộng số cuối nhân số số hạng chia 2
học tốt!!!
a) 12 + 15 + 18 + .. + 90
= ( 12 + 90 ) . [( 90 - 12 ) : 3 + 1 ] :2
= 102 . [ 78 : 3 + 1 ] : 2
= 102 . [ 26 +1 ] : 2
= 102 . 27 : 2
= 2754 :2
= 1377
a, \(\dfrac{1}{2}\) - ( - \(\dfrac{1}{3}\) ) + \(\dfrac{1}{23}\) + \(\dfrac{1}{6}\)
= \(\dfrac{5}{6}\) + \(\dfrac{1}{23}\) + \(\dfrac{1}{6}\)
= 1 + \(\dfrac{1}{23}\)
= \(\dfrac{24}{23}\)
b, \(\dfrac{11}{24}\) - \(\dfrac{5}{41}\) + \(\dfrac{13}{24}\) + 0,5 - \(\dfrac{36}{41}\)
= (\(\dfrac{11}{24}\) + \(\dfrac{13}{24}\)) - ( \(\dfrac{5}{41}\) + \(\dfrac{36}{41}\)) + 0,5
= 1 - 1 + 0,5
= 0,5
c,\(-\dfrac{1}{12}-\left(\dfrac{1}{6}-\dfrac{1}{4}\right)\)
=\(-\dfrac{1}{12}-\left(-\dfrac{1}{12}\right)\)
=0
d, \(\dfrac{1}{6}-\left[\dfrac{1}{6}-\left(\dfrac{1}{4}+\dfrac{9}{12}\right)\right]\)
= \(\dfrac{1}{6}-\left[\dfrac{1}{6}-1\right]\)
= \(\dfrac{1}{6}-\left(-\dfrac{5}{6}\right)\)
= 1
\(\frac{-7}{9}\cdot\frac{4}{11}+\frac{-7}{9}\cdot\frac{7}{11}+5\frac{7}{9}\)
\(=\frac{-7}{9}\cdot\left[\frac{4}{11}+\frac{7}{11}\right]+5\frac{7}{9}\)
\(=\frac{-7}{9}\cdot1+5+\frac{7}{9}\)
\(=\frac{-7}{9}+5+\frac{7}{9}=\frac{-7}{9}+\frac{7}{9}+5=5\)
\(\frac{-7}{9}.\frac{4}{11}+\frac{-7}{9}+\frac{7}{11}+5\frac{7}{9}\)
\(=\frac{-7}{9}.\left(\frac{4}{11}+\frac{7}{11}\right)+\frac{52}{9}\)
\(=\frac{-7}{9}.1+\frac{52}{9}\)
\(=\frac{-7}{9}+\frac{52}{9}\)
\(=\frac{45}{9}=5\)
0.306+0.2921
0.306--7/24
0.306--0.292
0.306+0.292
=0.597