a) 5.(-8).(-2).(-3)
=5.[(-8).(-2).(-3)]
=5.(-48)
=-240
b) 4.(–5)2 + 2.(–5) – 20
= 4.(-5)2 + 2.(-5) - (-4)(-5)
= (-5).[4.(-5) + 2 - (-4)]
= (-5).[-20 + 2 + 4]
=(-5).(-14)
=70
c) 27.(15 –12) – 15.(27 –12)
= 27.15 - 27.12 - 15.27 + 15.12
= (27.15 - 15.27) + (15.12 - 27.12)
= 0 + 15.12 - 27.12
= 12(15-27)
= 12.(-12)
= -144
d) - 126 – (42 – 5)2 + 870 : 29
= -126 - (16 - 5)2 + 30
= -126 - 112 + 30
= -126 - 121 + 30
= - 247 + 30
= -217
Chúc bạn học tốt!
\(a.5.\left(-8\right).\left(-2\right).\left(-3\right)\)
\(=\left[5.\left(-2\right)\right].\left[\left(-8\right).\left(-3\right)\right]\)
\(=-10.24\)
\(=-240\)
\(b.4.\left(-5\right)^2+2.\left(-5\right)-20\)
\(=4.\left(-5\right).\left(-5\right)+2.\left(-5\right)-20\)
\(=\left(-5\right).\left(-20\right)+2.\left(-5\right)-20\)
\(=\left(-20\right).\left[\left(-5\right)+1\right]+2.\left(-5\right)\)
\(=\left(-20\right).\left(-4\right)+2.\left(-5\right)\)
\(=80+\left(-10\right)\)
\(=70\)
\(c.27.\left(15-12\right)-15.\left(27-12\right)\)
\(=27.15-27.12-15.27+15.12\)
\(=\left(27.15-15.27\right)+\left(15.12-27.12\right)\)
\(=0+12.\left(15-27\right)\)
\(=0+12.\left(-12\right)\)
\(=-144\)
\(d.-126-\left(4^2-5\right)^2+870:29\)
\(=-126-\left(16-5\right)^2+30\)
\(=-126-11^2+30\)
\(=-126-121+30\)
\(=-217\)
a) 5 . (-8) . (-2) . (-3)
= [5 . (-2)] . [(-8) . (-3)]
= -10 . 24
= -240
b) 4 . (-5)2 + 2 . (-5) - 20
= 4 . (-5) . (-5) + 2 . (-5) - 20
= - 5 . (-20) + 2 . (-5) - 20
= 100 + (-10) - 20
= 90 - 20
= 70
c) 27 . (15 - 12) - 15 . (27 - 12)
= 27 . 15 - 27 . 12 - 15 . 27 - 15 . 12
= (27 . 15 - 15 . 27) - (15 . 12 - 27 . 12)
= 0 + 12 . (15 - 27)
= 12 . (-12)
= -144
d) -126 - (42 - 5)2 + 870 : 29
= -126 - (16 - 5)2 + 30
= -126 - 112 + 30
= -126 - 121 + 30
= -247 + 30
= -217
