125:25+12.4 25-(62-75)+(-38) 2680+[10.(4³-54):5²+2⁴]
Thực hiện phép tính:
a/ 125 : 25 + 12 . 4
c/ 2680 + [ 10 . ( 43 - 54 ) : 52 + 24 ]
b/ 25 - ( 62 - 75 ) + ( - 38 )
Giúp em nha
a) 125 : 25 + 12 . 4 c) 2680 + [ 10 . ( 43 -54 ) : 52 + 24]
= 5 + 48 = 2680 + [ 10 . ( 64 - 54 ) : 25 + 16]
= 53 = 2680 + [ 10 . 10 : 25 + 16]
= 2680 + [ 100 : 25 + 16]
= 2680 + [ 4 + 16 ]
= 2680 + 20
= 2700
a/ 125 : 25 + 12 . 4
=5+48
=53
c/ 2680 + [ 10 . ( 43 - 54 ) : 52 + 24 ]
=2680 + [ 10 . 10 : 25 + 16 ]
= 2680 + 20
=2700
b/ 25 - ( 62 - 75 ) + ( - 38 )
= 25 - (- 13) + (- 38)
=25 + 13 + (- 38)
=38 + (-38)
=0
Bài 1: Tính một cách hợp lí(tính nhanh)
a) (-25).5.(-4).2
b) (-456) - (67 - 456)
c) 78.45+145.(-78)
d) 38.( 62-75) + 62.(-75 - 38)
Bài 2: Tính hợp lí
a) 125.(-4).(-8).7
b) 35.67.137.(-35)
c) 72.( 28 - 49) + 28. _-49 - 72)
a) \(\left(-25\right).5.\left(-4\right).2\)
\(=\left[\left(-25\right).\left(-4\right)\right].\left(2.5\right)\)
\(=100.10=1000\)
b) \(\left(-456\right)-\left(67-456\right)\)
\(=-456-67+456\)
\(=\left(456-456\right)-67\)
\(=67\)
a) ((-25).(-4)).5.2
=100.10
=1000
b) (-456)-67+456
=(-456)+(-67)+456
=0+-(-67)
=-67
c)78.45+-145.78
=78.(45+145)
=78.190
=Tự làm
a) (-25).5.(-4).2
= 5 . ( -4 ) . ( -25 ) . 2
= -20 . ( - 50 )
= 100
b) (-456) - (67 - 456)
= -456 - 67 + 456
= -456 + 456 - 67
= -67
c) 78.45+145.(-78)
= 78 . 45 + ( - 145 ) . 78
= 78 . ( -145 + 45 )
= 78 . 100
= 7800
d) 38.( 62-75) + 62.(-75 - 38)
= 38 . 62 - 38 . 75 + 62 . ( - 75 ) - 62 . 38
= 38 . 62 - 62 . 38 + 38 . 75 + 62 . ( - 75 )
= 0 + 38 . 75 + ( - 62 ) . 75
= 75 . ( - 62 + 38 )
= 75 . ( - 24 )
= - 1800
a) 125.(-4).(-8).7
= 125 . ( - 8 ) . ( - 4 ) . 7
= 1000 . ( - 28 )
= - 28000
c) 72.( 28 - 49) + 28. ( -49 - 72)
= 72 . 28 - 72 . 49 + 28 . ( - 49 ) - 28 . 72
= 72 . 28 - 28 . 72 + 72 . 49 + 28 . ( - 49 )
= 0 + 72 . 49 + ( - 28 ) . 49
= 49 . ( -28 + 72 )
= 49 . 44
= 2156
bài 1 tính hợp lí (nếu có thể )
a)(-125).5.(-8).2
b)78.45+145.9.(-78)
c)(-456)-(67-456)
d)38.(62-75)+62.(-75-38)
e)(-50+19+143)-(-79+25+48
f)s2=1+(-3)+5+(-7)+...+(-1999)+2001
ai làm hết bài mình tích cho
cái này phải tự làm chứ???? Thế mới tốt lên được
(5346-2808):54+51
187.(38+62)-87.(62+38)
25.{32:[12-4+4.(16:8)]}
A=50+51+52+.......+99+100
(5346-2808) : 54 + 51
=2538 : 54 + 51
= 47 + 51 = 98
187 . ( 38 + 62 ) - 87 . (62 + 38 )
=187 . 100 - 87 . 100
= 100 . ( 187 - 87 )
= 100 . 100
= 10000
25. { 32 : [12 -4 + 4 . ( 16 : 8 )]}
= 25. { 32 : [12 - 4 + 8]}
= 25 . { 32 : [8 + 8 ]}
= 25 . { 32 : 16 }
= 25 . 2 =50
A = 50 +51 + 52 + ......+ 99+100
A = ( 100 + 50 ) . 51 : 2
A = 150 .51 : 2
A = 7650 : 2
A = 3825
Chuc ban hoc tot
\(\left(5346-2808\right):54+51\)
\(=2538:54+51\)
\(=47+51=98\)
\(187\left(38+62\right)-87\left(62+38\right)\)
\(=187.100-87.100\)
\(=100\left(187-87\right)\)
\(=100.100=10000\)
\(25\left\{32:\left[12-4+4\left(16:8\right)\right]\right\}\)
\(=25\left\{32:\left[12-4+4.2\right]\right\}\)
\(=25\left\{32:\left[12-4+8\right]\right\}\)
\(=25\left\{32:16\right\}\)
\(=25.2=50\)
\(A=50+51+52+......+100\)
\(=\dfrac{\left[\left(100-50\right):1+1\right]\left(100+50\right)}{2}\)
\(=3825\)
(5346 - 2808) : 54 + 51
= 2538 : 54 + 51
= 47 + 51
= 98
187 . (38 + 62) - 87 . (62 + 38)
= 187 . 100 - 87 . 100
= (187 - 87) . 100
= 100 . 100
= 10000
25 . {32 : [12 - 4 + 4 . (16 : 8)] }
= 25 . (32 : 8 + 4 . 2)
= 25 . (4 + 8)
= 25 . 4 + 25 . 8
= 100 . 200
= 20000
A = 50 + 51 + 52 +.......+ 99 + 100
A có : (100 - 50) : 1 + 1= 51 (phần tử)
\(\Rightarrow\) A = (100 + 50) . 51 : 2 = 3825.
12 x 62 x 3 + 6 mũ 2 x 38 - 125: 25
\(12.62.3+6^2.38-125:25\\ =36.62+36.38-5\\ =36.\left(62+38\right)-5\\ =36.100-5\\ =3600-5\\ =3595.\)
\(12\cdot62\cdot3+6^2\cdot38-125:25\)
\(=12\cdot62\cdot3+36\cdot38-5\)
\(=2232+1368-5\)
\(=3595\)
25 - ( 62 -75 ) + (- 38)
1/2×(2×x-3)+105/2=-137/2 A,-12×25-25×75-25×13 B,-50/7×49/10-35/2×-10/7+ -25/3× -9/5 C,-354+265-156+125 D,-74+40-50+16-35 E,-2/3×4/5+-4/5×4/3-0,125
1/2×(2×x-3)+105/2=-137/2
1/2×(2×x-3)=-137/2-105/2
1/2×(2×x-3)=-242/2
2×x-3=-242/2:1/2
2×x-3=-242
2.x=(-242)+3
2.x=239
x=239:2
x=239/2
A,-12×25-25×75-25×13
=[(-12)-75-13].25
=(-100).25
-2500
B,-50/7×49/10-35/2×-10/7+ -25/3× -9/5
=(-35)-(-25)+(-13)
=-23
C,-354+265-156+125
=[(-354)-156]+(265+125)
=(-510)+277
=-233
D,-74+40-50+16-35
=(-74)+40+(-50)+16+(-35)
=[(-74)+(-35)]+[40+(-50)+16]
=(-109)+26
=-83
E,-2/3×4/5+-4/5×4/3-0,125
=-2/3.4/5+4/5.(-4/3)-0,125
=4/5.[-2/3+(-4/3)]-0,125
=4/5.(-2)-0,125
=-8/5-0,125
=(-1,6)+(-0,125)
=-1,725
Bµi 1 1 37064 – 64 x 82 42966 217 2 320 – 120.5 95,25 5,25 874 12 x 12,53 132 x 9 132 4 48 x 17 48 x 3 5 56 x 27 56 x 35 62 6 45 x 48 – 90 x 24 145 7 754 x 75 – 2262 x 25 4568 8 1050 15 – 350 5 1769 4320 9 – 8640 18 750 10 316 192 384 321 108 11 24 25 26 ….. 124 125 126 12 154 – 153 152 – 151 150 – 149 ….. 4 – 3 2 – 113 37 x 38 – 19 x 74 1000 14 0.48 x 500 – 2.4 x 40 x 2
Bài 2: Tính
1) -25 + 13
2) -17 + 28
3) - 37 + 65;
4) (-4) . 51
5) 12 – 25
6) (-13) + (-30)
7) (-12) – 24
8) (-15) . (-11) + 123
9) (-150) : 3 + (-20).(-5)
10) (72 + 22 – 65) – (67 + 12 – 75)
Bài 3: Tính nhanh
1) - 138 + 57 + (-62) + 43
2) 12 – 17 + 38 – 43
3) 100 + ( -520) + 1140 + ( -620);
4) 15 . (-32) + 15 . (-42) + 15 . (-26)
Bài 4: Tìm x biết:
1) x + 49 = 31 2) 15 – x = 12 – (-19)
3) 2x – 20 = -14; 4) x + 79 = - 24
5) 36 – x = 12 – (-39) 6) x – 29 = -14;
7) x + 36 = 15 – ( -19) 8) 5x – 15 = - 225
Bài 5: Tìm tổng các số nguyên x ,biết:
1) 2) 3) 4)