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45- { [(120-60):15+5]:3} + (-55)
= 45 - { [60:15+5]:3} + (-55)
= 45 - {9:3} +(-55)
= 45 - 3 + (-55) = -13
b) \(6^2-2^3.5^0.6=36-8.1.6\)
\(36-48=-12\)
TICK MIK NHA
#)Giải :
\(\frac{1}{15}+\frac{4}{30}+\frac{9}{45}+\frac{16}{60}+...+\frac{81}{135}=\frac{1}{15}+\frac{2}{15}+\frac{3}{15}+...+\frac{9}{15}=\frac{45}{15}=3\)
Dễ ẹc ak :v rút gọn là ra
=(\(\frac{1}{15}\)+\(\frac{4}{30}\)+\(\frac{16}{60}\)+\(\frac{64}{120}\))+(\(\frac{9}{45}\)+\(\frac{36}{90}\))+(\(\frac{25}{75}\)+\(\frac{81}{135}\))
=(\(\frac{8}{120}\)+\(\frac{16}{120}\)+\(\frac{32}{120}\)+\(\frac{64}{120}\))+(\(\frac{18}{90}\)+\(\frac{36}{90}\))+\(\frac{14}{15}\).
=1+\(\frac{3}{5}\)+\(\frac{14}{15}\).
=\(\frac{8}{5}\)+\(\frac{14}{15}\).
=\(\frac{15}{38}\)
a) 576 : x - 30 = 2
576 : x = 2 + 30
576 : x = 32
x = 576 : 32
x = 18
b) 180 - ( x - 45 ) : 2 = 120
( x - 45 ) : 2 = 180 - 120
( x - 45 ) : 2 = 60
x - 45 = 60 * 2
x - 45 = 120
x = 120 + 45
x = 165
a﴿ 576 : x ‐ 30 = 2
576 : x = 2 + 30
576 : x = 32
x = 576 : 32
x = 18
b﴿ 180 ‐ ﴾ x ‐ 45 ﴿ : 2 = 120
﴾ x ‐ 45 ﴿ : 2 = 180 ‐ 120
﴾ x ‐ 45 ﴿ : 2 = 60
x ‐ 45 = 60 * 2
x ‐ 45 = 120
x = 120 + 45
x = 165
\(45+120\div x=60\)
\(\Leftrightarrow120\div x=15\)
\(\Leftrightarrow x=8\)
\(45+\frac{120}{x}=60\left(đk:x\ne0\right)\)
\(< =>\frac{120}{x}=60-45\)
\(< =>\frac{120}{x}=15\)
\(< =>x.15=120\)
\(< =>x=\frac{120}{15}=8\)
1)
a) 2x + 5 = 3⁴ : 3²
2x + 5 = 3²
2x + 5 = 9
2x = 9 - 5
2x = 4
x = 4 : 2
x = 2
b) (3x - 24).73 = 2.74
(3x - 24).73 = 148
3x - 24 = 148/73
3x = 148/73 + 24
3x = 1900/73
x = 1900/73 : 3
x = 1900/219
c) [3.(42 - x)] + 15 = 23.3
126 - 3x + 15 = 69
141 - 3x = 69
3x = 141 - 69
3x = 72
x = 72 : 3
x = 24
d) 126 + (132 - x) = 300
132 - x = 300 - 126
132 - x = 174
x = 132 - 174
x = -42
2)
a) 120 - (x + 55) = 60
x + 55 = 120 - 60
x + 155 = 60
x = 60 - 55
x = 5
b) (7x - 11).3 = 25.52 + 200
(7x - 11).3 = 1500
7x - 11 = 1500 : 3
7x - 11 = 500
7x = 500 + 11
7x = 511
x = 511 : 7
x = 73
c) 2x + 2x + 4 = 544
4x = 544 - 4
4x = 540
x = 540 : 4
x = 135
45 - { [ ( 120-60) : 15 +6 ] : 2 }
= 45 - { [ 60 : 15 + 6 ] : 2 }
= 45 - { [ 4 + 6 ] : 2 }
= 45 - 10 : 2
= 45 - 5
= 40
45-{[(120-60):15+6]:2}
=45-{[60:15+6]:2}
=45-{[4+6]:2}
=45-{10:2}
=45-5
=40