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a) \(x+5=20-\left(12-7\right)\)
\(\Rightarrow x+5=20-5\)
\(\Rightarrow x+5=15\)
\(\Rightarrow x=15-5\)
\(\Rightarrow x=10\)
b) \(15-\left(3+2x\right)=2^2\)
\(\Rightarrow3+2x=15-4\)
\(\Rightarrow3+2x=11\)
\(\Rightarrow2x=11-3\)
\(\Rightarrow2x=8\)
\(\Rightarrow x=\dfrac{8}{2}\)
\(\Rightarrow x=4\)
c) \(-11-\left(19-x\right)=50\)
\(\Rightarrow19-x=-11-50\)
\(\Rightarrow19-x=-61\)
\(\Rightarrow x=61+19\)
\(\Rightarrow x=80\)
d) \(159-\left(25-x\right)=43\)
\(\Rightarrow25-x=159-43\)
\(\Rightarrow25-x=116\)
\(\Rightarrow x=25-116\)
\(\Rightarrow x=-91\)
e) \(\left(79-x\right)-43=-\left(17-52\right)\)
\(\Rightarrow\left(79-x\right)-43=52-17\)
\(\Rightarrow79-x-43=35\)
\(\Rightarrow36-x=35\)
\(\Rightarrow x=1\)
f) \(\left(7+x\right)-\left(21-13\right)=32\)
\(\Rightarrow7+x-8=32\)
\(\Rightarrow x-1=32\)
\(\Rightarrow x=32+1\)
\(\Rightarrow x=33\)
g) \(-x+20=-15+8+13\)
\(\Rightarrow-x+20=6\)
\(\Rightarrow x=20-6\)
\(\Rightarrow x=14\)
h) \(-\left(-x+13-142\right)+18=55\)
\(\Rightarrow x-13+142+18=55\)
\(\Rightarrow x+147=55\)
\(\Rightarrow x=55-147\)
\(\Rightarrow x=-92\)
Lời giải:
c. $=20:(-2)+12.5=-10+60=50$
d. $204:[80-(35-23)]+1=204:68+1=3+1=4$
c. =20:(−2)+12.5=−10+60=50=20:(−2)+12.5=−10+60=50
d. 204:[80−(35−23)]+1=204:68+1=3+1=4
\(=60-\dfrac{\left[36+64\right]}{25}\)
\(=60-4=56\)
12517 \(=\left(5^3\right)^{17}=5^{51}\)
\(625^{13}=\left(5^4\right)^{13}=5^{52}\)
Ta có:
551 < 552
\(\Rightarrow\) 12517 < 62513
Ta có:8=23
10=2.5
24=24.5
BCNN(...)=23.5=24.5=40
b)Ta có:
16=24
24=23.3
BCNN(...)=24.3=48
c)Ta có:
60=22.3.5
140=22.5.7
BCNN(...)=22.3.5.7=420
Mấy bài sau bn cứ lm như thế này nhé^^
a) 8 = 2³
10 = 2.5
20 = 2².5
BCNN(8; 10; 20) = 2³.5 = 40
b) 16 = 2⁴
24 = 2³.3
BCNN(16; 24) = 2⁴.3 = 48
c) 60 = 2².3.5
140 = 2².5.7
BCNN(60; 140) = 2².3.5.7 = 420
d) 8 = 2³
9 = 3²
11 = 11
BCNN(8; 9; 11) = 2³.3².11 = 792
e) 24 = 2³.3
40 = 2³.5
162 = 2.3⁴
BCNN(24; 40; 162) = 2³.3⁴.5 = 3240
f) 56 = 2³.7
70 = 2.5.7
126 = 2.3².7
BCNN(56; 70; 126) = 2³.3².5.7 = 2520
g) 28 = 2².7
20 = 2².5
30 = 2.3.5
BCNN(28; 20; 30) = 2².3.5.7 = 420
h) 34 = 2.17
32 = 2⁵
20 = 2².5
BCNN(34; 32; 20) = 2⁵.5.17 = 2720
k) 42 = 2.3.7
70 = 2.5.7
20 = 2².5
BCNN(42; 70; 20) = 2².3.5.7 = 420
l) 9 = 3²
10 = 2.5
11 = 11
BCNN(9; 10; 11) = 2.3².5.11 = 990
a: =321-21*[(2*27+16:32)-52]
=321-21*[2+0,5]
=321-21*2,5=268,5
b: \(=\dfrac{160}{17+\left[9\cdot5\left(14+8\right)\right]}\)
\(=\dfrac{160}{17+45\cdot22}=\dfrac{160}{1007}\)
c: =100*9:3^2=100
d: =2*27+143:(36-25)
=54+143:11
=54+13=67
22 x 43 - 625 : {[504 - (52 x 8 + 70) : 32 + 6] : 20 + 20230}
= 4 x 64 - 625 : {[504 - (25 x 8 + 70) : 9 + 6] : 20 + 1}
= 256 - 625 : {[504 - (200 + 70) : 9 + 6] : 20 + 1}
= 256 - 625 : {[504 - 270 : 9 + 6] : 20 + 1}
= 256 - 625 : {[504 - 30 + 6] : 20 + 1}
= 256 - 625 : {[474 + 6] : 20 + 1]
= 256 - 625 : {480 : 20 + 1]
= 256 - 625 : {24 + 1}
= 256 - 625 : 25
= 256 - 41
= 215
22 x 43 - 625 : {[504 - (52 x 8 + 70) : 32 + 6] : 20 + 20230}
= 4 x 64 - 625 : {[504 - (25 x 8 + 70) : 9 + 6] : 20 + 1}
= 256 - 625 : {[504 - (200 + 70) : 9 + 6] : 20 + 1}
= 256 - 625 : {[504 - 270 : 9 + 6] : 20 + 1}
= 256 - 625 : {[504 - 30 + 6] : 20 + 1}
= 256 - 625 : {[474 + 6] : 20 + 1]
= 256 - 625 : {480 : 20 + 1]
= 256 - 625 : {24 + 1}
= 256 - 625 : 25
= 256 - 41
= 215