Tính 144 3 4 : 9 3 4
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\(\frac{4}{3}.\frac{9}{8}.\frac{16}{15}.\frac{25}{24}...\frac{121}{120}.\frac{144}{143}\)
\(=\frac{2.2}{1.3}.\frac{3.3}{2.4}.\frac{4.4}{3.5}.\frac{5.5}{4.6}...\frac{11.11}{10.12}.\frac{12.12}{11.13}\)
\(=\frac{2.2.3.3.4.4.5.5...11.11.12.12}{1.3.2.4.3.5.4.6...10.12.11.13}\)
\(=\frac{\left(2.3.4.5...11.12\right).\left(2.3.4.5...11.12\right)}{\left(1.2.3.4...10.11\right).\left(3.4.5.6...12.13\right)}\)
\(=\frac{12.2}{1.13}\)
\(=\frac{24}{13}\)
( Dấu \(.\)là dấu \(\times\)nha )
a) \(A=\left\{x\in N|0\le x\le4\right\}\)
b) \(B=\left\{x\in N|x=4k;0\le k\le4;k\in N\right\}\)
c) \(C=\left\{x\in Z|x=\left(-3\right)^k;1\le k\le4;k\in N\right\}\)
d) \(D=\left\{x\in N|x=k^2;k=3a;1\le a\le4;a\in N\right\}\)
a)
160 : (4 × 8) = 160 : 32 = 5
160 : 4 : 8 = 40 : 8 = 5
Vậy 160 : (4 × 8) = 160 : 4 : 8.
96 : (3 × 8) = 96 : 24 = 4
96 : 3 : 8 = 32 : 8 = 4
Vậy 96 : (3 × 8) = 96 : 3 : 8.
105 : (5 × 7) = 105 : 35 = 3
105 : 5 : 7 = 21 : 7 = 3
Vậy 105 : (5 × 7) = 105 : 5 : 7.
Nhận xét: a : (b × c) = a : b : c
b)
270 : (9 × 6) = 270 : 9 : 6 = 30 : 6 = 5
420 : (7 × 3) = 420 : 7 : 3 = 60 : 3 = 20
144 : (2 × 8) = 144 : 2 : 8 = 72 : 8 = 9
B={x\(\in\)N|x=3k; 1<=k<=4}
C={x\(\in\)N|x=4*a2; 1<=a<=5}
D={x\(\in\)N|x=9*a2;1<=a<=4}
E={x\(\in\)N|x=4k; 0<=x<=4}
G={x\(\in\)N|x=(-3)^k; 1<=k<=4}
1)-7264+(1543+7264)=-7264+1543+7264=1543
2)(144-97)-144=144-97-144=-97
3)(-145)-(18-145)=-145-18+145=-18
4)111+(-11+27)=111-11+27=100+27=127
5)(27+514)-(486-73)=27+514-486-73=541-486-73=55-73=-18
6)(36+79)+(145-79-36)=36+79+145-79-36=145
7)10-[12-(-9-1)]=10-[12+9+1]=10-12-9-1=-12
8)(38-29+43)-(43+38)=38-29+43-43-38=-29
9)271-[(-43)+271-(-17)]=271-[-43+271+17]=271+43-271-17=43-17=26
10)-144-[29-(+144)-(+144)]=-144-[29-144-144]=-144-29+144+144=-29+144=115
a) \(\left(x-\dfrac{1}{4}\right)^2=\dfrac{4}{9}\)
\(\left(x-\dfrac{1}{4}\right)^2=\left(\dfrac{2}{3}\right)^2\)
\(x-\dfrac{1}{4}=\dfrac{2}{3}\)
\(x=\dfrac{2}{3}+\dfrac{1}{4}\)
\(x=\dfrac{8}{12}+\dfrac{3}{12}\)
\(x=\dfrac{11}{12}\)
\(\)
mk ko ghi lại đề bài nha bạn
1. =-7624+1543+7264 = (-7264+7264)+1543
= 0+1543
= 1543
2. = 144 - 97 - 144 = ( 144 -144 ) -97
= 0-97
= 0+ (-97)
= -97
3. = -145 - 18 + 145 = (-145+145)-18
= 0-18
= 0+ (-18)
= -18
4. = 111+ (-11) + 27 = [ 111+ (-11) ] +27
= 100+27
= 127
5. = 27+ 514 - 486 + 73 = ( 27+ 73) + ( 514 - 486)
= 100 + 28
= 128
6. = 36 + 79 +145 -79 -36 = ( 36-36)+(79-79)+145
= 0+0+145
= 145
7. = 10-12-(-9)+1 = 10 + (-12) + 9 +1
= (10+9+1) +(-12)
= 20+(-12)
= 8
8. = 38 -29 +43 -43 -38 =(38-38)+(43-43)-29
= 0+0 -29
= 0+ (-29)
= -29
9. = 271 - (-43) -271 - (-17)=271+43-271+17
= (271-271) + ( 43 +17)
= 0+ 60
= 60
10. = -144 - 29 + (-144) + (-144) = -144 + (-29) + (-144) +(-144)
= [-144 + (-144)+ (-144)] + (-29)
= -144 x3 + (-29)
= -432 + (-29)
= -461
k mk nha bạn