a.2.3/5:2.1/4+5/2
=2.3.4/5.2.1+5/2
=3.4/5+5.2
=12/5+5/2=24/10+25/10=49/10
b.16/6-2.1/6:1.1/7
=16/6-2/6.1/7
=16/6-2/42
=55/21
a)2×3/5÷2×1/4+5/2
=6/5÷1/2+5/2
=12/5+5/2
=49/10
b)16/6-2×1/6÷1×1/7
=8/3-1/3÷1/7
=8/3-7/3
=1/3
a.2.3/5:2.1/4+5/2
=2.3.4/5.2.1+5/2
=3.4/5+5.2
=12/5+5/2=24/10+25/10=49/10
b.16/6-2.1/6:1.1/7
=16/6-2/6.1/7
=16/6-2/42
=55/21
a)2×3/5÷2×1/4+5/2
=6/5÷1/2+5/2
=12/5+5/2
=49/10
b)16/6-2×1/6÷1×1/7
=8/3-1/3÷1/7
=8/3-7/3
=1/3
2.1+2.2+2.3+2.4+......+2.25
RÚT GỌN
\(a,\dfrac{121.75.130.169}{39.60.11.198}\)
\(b,\dfrac{\left(3.4.2^{16}\right)^2}{11.2^{13}.4^{11}.16^9}\)
\(c,\dfrac{5.\left(2^2.3^2\right)^9.\left(2^2\right)^6-2.\left(2^2.3\right)^{14}.3^6}{5.2^{28}.3^{19}-7.2^{29}.3^{18}}\)
TÍNH HỢP LÍ
\(a,\left(10^2+11^2+12^2\right):\left(13^2+14^2\right)\)
TÍNH NHANH
\(a,13-12+11+10-9+8-7-6+-4+3+2-1\)
Tính giá trị của các biểu thức sau: 5/2.1+4/1.11+3/11.2+1/2.15+13/15.4
Tính giá trị biểu thức : A= \(\dfrac{5\left(2^2.3^2\right)^9.\left(2^2\right)^6-2\left(2^2.3\right)^{14}.3^4}{5.2^{28}.3^{18}-7.2^{29}.3^{18}}\)
Thực hiện phép tính: A= 5.(2^2.3^2)^9.(2^2)^6-2.(2^2.3)^14.3^4/5.2^28.3^18-7.2^29.3^18
so sánh A=4/7+5+3/7^2+5/7^3+6/7^4
B=5/7^4+5+6/7^2+4/7+5/7^3
Bài 1. Tính hợp lý
1) (–12) +6.(–3)
2) (36 -2020) + (2019 -136) – 27
3) (144 – 97) – (244 – 197)
4) (–24).13 – 24.( –3)
5) 54+55+56+57+58-(64+65+66+67+68)
6) 24(16 – 5) – 16(24 – 5)
7) 47.(23 + 50) – 23.(47 + 50)
8) (-31). 47 + (-31). 52 + (-31)
Bài 2: Tìm số nguyên x, biết:
1)-17-(2x-5)=-6
2) 10-2(4-3x)=-4
3)-12+3(-x+7)=-18
4)-45:[5.(-3-2x)]=3
5) x.(x+3)=0
6) (x-2).(x+4)=0
7) x.(x+1).(x-3)=0
Baj 1. Tjnh Tông
a) A= 8+12+16+20+........+100
b) B= 5+52+56+510+514+...............+5100
c) C= 1.2+2.3+3.4+4.5+5.6+6.7+7.8+8.9+9.10
Baj 2. Chứng mjnh rằng:
a) A= 2+22+23+24+25+.........+260 chja hết cho 21 và 15
b) B= 1+3+32+33+34+.........+311 chja hết cho 52
thu gọn các biểu thức sau
a)C=3^14+3^15+3^16+3^17+...+3^n
b)D=3^11+3^14+3^17+3^20+...+3^2021
c) E= -5^2-5^4-5^6-5^8-...-5^1000
d)F=-5^21-5^23-5^25-5^27-...-5^2019
e)M=7^2-7^4+7^6-7^8+...-7^1000
d)N=-12+11^2+11^3-11^4-11^5+...+11^498+11^499