Question

Bài 5: Tính hợp lí:

a. (43 − 13) ⋅ (−3) + 27 ⋅ (−14 − 16)

b. (−72) ⋅ (34 − 12) − 34 ⋅ (12 − 72)

c. (−127) ⋅ (1 − 582) − 582.127

d. −225.35 + 225.136 − 225

e. 125. (−7) ⋅ (−2) 3 ⋅ (−1) 2𝑛 (𝑛 ∈ ℕ)

f. 1 − 2 + 3 − 4 + 5 − 6 + ⋯ + 199 − 2 

Answer 1

a, (43 - 13).(-3) + 27.(-14 - 16)

= 30.(-3) + 27.(-30)

= - 30.(3 + 27)

= -30.30

= -900

Answer 2

b, (-72).(34 -12) - 34.(12 - 72)

= -72.34 + 72.12 - 34.12 + 34.72

= (-72.34 + 34.72) + 12.(72 - 34)

= 12.38

= 456

Answer 3

c, (-127).(1 - 582)  - 582.127

= - 127  + 582.127 - 582.127

=  - 127 

Answer 4

d, - 225.35 + 225.136 - 225

= - 225 .(35 - 136 + 1)

= - 225 . 100

= - 22500 

Answer 5

e, 125. (-7).(-2).3 (-1).2n

= (125.(-2). (-1). 2). (-7).3.n

= 125.4.(-21).n

= 500.(-21).n

= - 10500n