a) (37 – 17).(-5) + 23.(-13 – 17) b) (-57).(67 – 34) – 67.(34 – 57) 13/09/2021 Bởi Ximena a) (37 – 17).(-5) + 23.(-13 – 17) b) (-57).(67 – 34) – 67.(34 – 57)
Đáp án: a) (37 – 17) . (–5) + 23 . (–13 – 17) = 20 . (–5) + 23. (–30) = (–100) + (–690) = –790. b) *Cách 1: (–57) . (67 – 34) – 67 . (34 –57) = [(–57) . 67 – (–57 ) . 34] – (67 . 34 – 67 . 57) = – (57 . 67) – [–(57 . 34)] – (67 . 34 – 67 . 57) = – 57 . 67 + 57 . 34 – 67 . 34 + 67 . 57 = 67 . 57 – 57. 67 + 57 . 34 – 67 . 34 = 0 + 34 . (57 – 67) = 34 . (–10) = –340 *Cách 2: (–57) . (67 – 34) – 67 . (34 –57) = (–57) . 33 – 67 . (-23) = -1881 + 1541 = -340 5* and CTLHN! Bình luận
Đáp án:a)-790 b)-340 Giải thích các bước giải: a)(37-17).(-5)+23(-13-17) =20.(-5)+23(-30)=-100-690 =-790 b)(-57).(67-34)-67.(34-57) =(-57).33-67.(-23) =1881+1541 =-340 Bình luận
Đáp án:
a) (37 – 17) . (–5) + 23 . (–13 – 17)
= 20 . (–5) + 23. (–30)
= (–100) + (–690) = –790.
b) *Cách 1:
(–57) . (67 – 34) – 67 . (34 –57)
= [(–57) . 67 – (–57 ) . 34] – (67 . 34 – 67 . 57)
= – (57 . 67) – [–(57 . 34)] – (67 . 34 – 67 . 57)
= – 57 . 67 + 57 . 34 – 67 . 34 + 67 . 57
= 67 . 57 – 57. 67 + 57 . 34 – 67 . 34
= 0 + 34 . (57 – 67)
= 34 . (–10) = –340
*Cách 2:
(–57) . (67 – 34) – 67 . (34 –57)
= (–57) . 33 – 67 . (-23)
= -1881 + 1541
= -340
5* and CTLHN!
Đáp án:a)-790
b)-340
Giải thích các bước giải:
a)(37-17).(-5)+23(-13-17)
=20.(-5)+23(-30)
=-100-690
=-790
b)(-57).(67-34)-67.(34-57)
=(-57).33-67.(-23)
=1881+1541
=-340