tinh nhanh a, 2.53.12+46.87-3.8.40 b ,5.7.77-7.60=49.25-15.42 c, 135.99 d,(56.27+56.35):62 e 420+65.4=(x+175):5+30 f ,(x:23+45).67+8911 g, [ 250-250) ]:x=(450-60);130 h; (32.15) :2=( x+70):14-40
tinh nhanh a, 2.53.12+46.87-3.8.40 b ,5.7.77-7.60=49.25-15.42 c, 135.99 d,(56.27+56.35):62 e 420+65.4=(x+175):5+30 f ,(x:23+45).67+8911 g, [ 250-250) ]:x=(450-60);130 h; (32.15) :2=( x+70):14-40
Đáp án:
Giải thích các bước giải:
a, 2.53.12+46.87-3.8.40
= 24×53 + 4x6x87 – 24×40
= 24(53+40) + 4x6x87
= 24 x 93 + 24×87
= 24(93 + 87)
= 24 x 180 = 4320
c, 135.99 = 135 ( 100 – 1) = 13500 – 135 = 13365
d,(56.27+56.35):62 = 56 ( 27 + 35 ) / 62 = 56 x 62 / 62 = 56
e 420+65.4=(x+175):5+30
420 + 260 – 30 = (x+175)/5
650 / 5 – 175 = x
=> x = -45
g, [ 250-250) ]:x=(450-60);130
0 /x = 3
x = Tất cả các số nguyên ( trừ 0)
h; (32.15) :2=( x+70):14-40
(240 + 40) x 14 -70 = x
=> x = 3850
a,
2.53.12+46.87-3.8.40
= 24×53 + 4x6x87 – 24×40
= 24(53+40) + 4x6x87
= 24 x 93 + 24×87
= 24(93 + 87)
= 24 x 180 = 4320
b,
5.7.77-7.60+49.25-15.42
= 5.7.7.11- 7.5.12+ 7.7.5.5- 5.3.7.6
= 7.5( 77- 12+ 35- 18)
= 35.82
= 2870
c,
135.99 = 135 ( 100 – 1)
= 13500 – 135
= 13365
d,
(56.27+56.35):62
= 56. ( 27 + 35 ) ÷ 62
= 56 . 62÷62
= 56.1
=56
e
420+65.4=(x+175):5+30
<=> 420 + 260 = ( x + 175 ) : 5 +30
<=> 680 = ( x + 175 ) : 5 +30
=> ( x + 175 ) : 5 = 650
=> x + 175 = 650. 5 = 3250
=> x = 3250 – 175 = 3075
h
32.15) :2=( x+70):14-40
<=>(240 + 40).14 -70 = x
<=>280.14-70=x
<=>x=3850
g
250-250) :x=(450-60):130
<=> 0 : x = (450-60):130
=> xϵϕ