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a) -321 + (-29) - 142 - (-72)
= [-321 +(-29)]+ [(-142) + 72]
= [-(321 + 29)] + [- (142 - 72)]
= (-350) + (-70)
= -(350 + 70)
= -420
b) 214 - (-36) + (-305)
= 214 + 36 - 305
= 250 - 305
= -(305 - 250)
= -55.
a, -321 + (-29 ) - 142 - (-72) = -321 - 29 - 142 + 72 = -420.
b, 214 - (-36) + (-305) = 214 + 36 - 305 = -55.
c, 232 - (581 + 132 - 331) = 232 - 581 - 132 + 331 = -150.
d, [ 12+ (-57)] - [-57 - (-12) = 12 - 57 + 57 - 12 = 0.
\(\dfrac{3}{17}\) .\(\dfrac{6}{29}\) - \(\dfrac{3}{17}\).\(\dfrac{35}{29}\) + 2022\(\dfrac{3}{17}\)
= (\(\dfrac{3}{17}\).\(\dfrac{6}{29}\) - \(\dfrac{3}{17}\).\(\dfrac{35}{29}\)) + 2022 + \(\dfrac{3}{17}\)
= \(\dfrac{3}{17}\).(\(\dfrac{6}{29}\) - \(\dfrac{35}{29}\)) + 2022 + \(\dfrac{3}{17}\)
= \(\dfrac{3}{17}\).(-1) + 2022 + \(\dfrac{3}{17}\)
= (- \(\dfrac{3}{17}\) + \(\dfrac{3}{17}\)) + 2022
= 0 + 2022
= 2022
b; \(\dfrac{5}{6}\) - (\(\dfrac{1}{3}\) + \(\dfrac{1}{2}\)).20%
= \(\dfrac{5}{6}\) - \(\dfrac{5}{6}\).\(\dfrac{1}{5}\)
= \(\dfrac{5}{6}-\dfrac{1}{6}\)
= \(\dfrac{4}{6}\)
= \(\dfrac{2}{3}\)
b. 7 + (-12 + 43) - [2 + (19 - 34)]
= 7+31- [2+(-15)]
= 7+31-(-13)
= 51
a) Xem lại đề.
b) 5. (x - 3)2 + 17 = 142
5. (x - 3)2 = 142 - 17
5. (x - 3)2 = 125
(x - 3)2 = 125 : 5
(x - 3)2 = 25
(x - 3)2 = 52 (cùng số mũ)
⇒ x - 3 = 5
x = 5 + 3 = 8
c) [(6x - 72) : 2 - 84] . 28 = 5628
[(6x - 72) : 2 - 84] = 5628 : 28
[(6x - 72) : 2 - 84] = 201
(6x - 72) : 2 = 201 + 84
(6x - 72) : 2 = 285
6x - 72 = 285. 2
6x - 72 = 570
6x = 570 + 72
6x = 642
x = 642 : 6
x = 107
\(-321+\left(-29\right)-142-a\left(-72\right)\)
\(=\left(-321-29-142\right)+72a\)
\(=-492+72a\)