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tính hợp lý nếu có thể
a) 2.25.9.4
b)35.112-12.35+50
c)16+(516 : 514 - 90)
d) 24.7 - [181 - ( 13 - 4)2 ]
a: \(2\cdot25\cdot9\cdot4=25\cdot4\cdot9\cdot2=18\cdot100=1800\)
b: \(35\cdot112-12\cdot35+50\)
\(=35\left(112-12\right)+50\)
=3500+50
=3550
c: \(16+\left(5^{16}:5^{14}-9^0\right)\)
\(=16+5^2-1\)
=25+15
=40
d: \(24\cdot7-\left[181-\left(13-4\right)^2\right]\)
\(=168-181+9^2\)
=81-13
=68
a)2.25.9.4
=(25.4).(9.2)
=100.18
1800
b)35.112-12.35+50
=35.(112-12)+50
=35.100+50
=3500+50
=3550
c)\(16+\left(5^{16}:5^{14}-9^0\right)\)
\(=16+\left(5^2-9^0\right)\)
\(=16+\left(25-1\right)\)
\(=16+24\)
\(=40\)
d)\(24.7-[181-\left(13-4\right)^2]\)
\(=24.7-[181-9^2]\)
\(=24.7-[181-81]\)
\(=24.7-100\)
\(=168-100\)
\(=68\)
\(\left(\frac{1}{9}\right)^{2016}.9^{2016}-96^2:24^2=\frac{1^{2016}}{9^{2016}}.9^{2016}-\left(\frac{96}{24}\right)^2\)\(=1-4^2=1-16=-15\)
Theo quy tắc của dấu ngoặc,ta có:
516+320+357+5000+612-(516+320)-(5000+357+612)+(-420)+(-580)
= 516+320+357+5000+612-516-320-5000-357-612+(-420)+(-580)
= (516-516)+(320-320)+(357-357)+(5000-5000)+(612-612)+(-420)+(-580)
= 0 + 0 + 0 + 0 + 0 + (-420)+(-580)
= 0 + 0 + 0 + 0 + (-420)+(-580)
= 0 + 0 + 0 + (-420)+(-580)
= 0 + 0 + (-420)+(-580)
= 0 + ((-420)+(-580))
= 0 + -1000
= -1000
\(\text{( -12 ) + ( -13 ) + 36 + ( - 11 )}\)
\(=\left[\left(-12\right)+\left(-13\right)+\left(-11\right)\right]+36\)
\(=\left(-36\right)+36\)
\(=0\)
\(\text{- 16 + 24 + 16 _ 34}\)
\(=\left(-16+16\right)+\left(24-34\right)\)
\(=0+\left(-10\right)\)
\(=-10\)
\(\text{25 + 37 _ 48 _ 25_ 37}\)
\(=\left(25-25\right)+\left(37-37\right)-48\)
\(=0+0-48\)
\(=-48\)
\(\text{2575 + 37 _ 2576 _ 29}\)
\(=\left(2575-2576\right)+\left(37-29\right)\)
\(=\left(-1\right)+8\)
\(=7\)
\(\text{34 + 35 + 36 + 37 _ 14 _ 15 _ 16 _ 17}\)
\(=\left(34-14\right)+\left(35-15\right)+\left(36-16\right)+\left(37-17\right)\)
\(=10+10+10+10\)
\(=40\)
\(\text{( 27 + 514 ) _ ( 486 _ 73 )}\)
\(=27+514-486+73\)
\(=\left(27+73\right)+\left(514-486\right)\)
\(=100+28\)
\(=128\)
chúc bạn học tốt
Bài 1: tính hợp lí:
( -12 ) + ( -13 ) + 36 + ( - 11 )
= [ - 12 + ( - 13 ) + ( - 11 ) ] + 36
= ( - 36 ) + 36
= 0
- 16 + 24 + 16 - 34
= ( - 16 + 16 ) + ( 24 - 34 )
= 0 + ( - 10 )
= - 10
25 + 37 - 48 - 25 - 37
= ( 25 - 25 ) + ( 37 - 37 ) - 48
= 0 + 0 - 48
= - 48
2575 + 37 - 2576 - 29
= ( 2575 - 2576 ) + ( 37 - 29 )
= - 1 + 8
= 7
34 + 35 + 36 + 37 - 14 - 15 - 16 - 17
= ( 34 - 14 ) + ( 35 - 15 ) + ( 36 - 16 ) + ( 37 - 17 )
= 20 + 20 + 20 + 20
= 20 x 4
= 80
Bài 2: bỏ dấu ngoặc rồi tính:
( 27 + 514 ) - ( 486 - 73 )
= 27 + 514 - 486 + 73
= ( 27 + 73 ) + ( 514 - 486 )
= 100 + 28
= 128
\(\left(x-3\right):2=\dfrac{514}{512}\)
\(\Rightarrow\left(x-3\right):2=\dfrac{257}{256}\)
\(\Rightarrow x-3=\dfrac{257}{128}\)
\(\Rightarrow x=\dfrac{641}{128}\)
\(\left(x-3\right):2=\dfrac{514}{512}\)
\(\Leftrightarrow x-3=\dfrac{257}{128}\)
hay \(x=\dfrac{641}{128}\)
Theo quy tắc của dấu ngoặc,ta có:
516+320+357+5000+612-(516+320)-(5000+357+612)+(-420)+(-580)
= 516+320+357+5000+612-516-320-5000-357-612+(-420)+(-580)
= (516-516)+(320-320)+(357-357)+(5000-5000)+(612-612)+(-420)+(-580)
= 0 + 0 + 0 + 0 + 0 + (-420)+(-580)
= 0 + 0 + 0 + 0 + (-420)+(-580)
= 0 + 0 + 0 + (-420)+(-580)
= 0 + 0 + (-420)+(-580)
= 0 + (-420)+(-580)
= (-420)+(-580)
= -1000
\(x+\left(x-1\right)+\left(x-2\right)+...+\left(x-101\right)=-516\)
\(x+x-1+x-2+...+x-101=-516\)
\(\left(x+x+...+x\right)-\left(1+2+...+101\right)=-516\)
\(102x-\left[\left(101+1\right)101:2\right]=-516\)
\(102x-5151=-516\)
\(102x=4635\)
\(x=\dfrac{1545}{34}\)
516:514+24×2-2016
=516-14 + 24+1 - 2016
=52 + 25 - 2016
= 25 + 32 - 2015
= -1959