5+3=28
9+1=810
8+6=214
5+4=19
7+3=?
5+3=28
9+1=810
8+9=214
5+4=19
7+2=?
a, 1-2+3-4+5-6+....+2021-2022
b, 1-6+2-7+3-8+4-9+.......+35-40
c, -1+2-3+4-5+6-.........-2021+2022
d, 1-4+2-5+3-6+.....+197-200
e, -1-2-3-4-5-....-199-200
a: =(-1)+(-1)+...+(-1)=-1011
b: =(-5)+(-5)+...+(-5)=-175
a) ( 19 4 + 21 3 ).( 20 5 - 15 3 ).( 6 2 - 2 8 )
b) 5 2 . 197 + 197. 2 3 + 197. 59
a)=407.52.34
=21164.34
=719576
b)=197.(52+23+59)
=197.134
=26398
a, (4^19 + 3^21) . (5^20 - 3^15) . (2^6 - 8^2)
b, 2^5 . 197 + 197 . 3^2 + 197 . 59
\(a,\left(4^{19}+3^{21}\right).\left(5^{20}-3^{15}\right).\left(2^6-8^2\right)\\ =\left(4^{19}+3^{21}\right).\left(5^{20}-3^{15}\right).\left(2^{3.2}-2^{3.2}\right)\\ =\left(4^{19}+3^{21}\right).\left(5^{20}-3^{15}\right).0=0\)
\(b,2^5.197+197.3^2+197.59\\ =197.32+197.9+197.59\\ =197.\left(32+9+59\right)\\ =197.100=19700\)
a) 5√1,96 - 4√2,25 + 3√1,69
b) 1/3√49 + 3/4√324 - 2/3√400
c) 5/6√289 - 1/2√256 + 2/5√225
d) 15√16/25 + 12√9/16 - 18√16/81
a: =5*1,4-4*1,5+3*1,3
=7-6+3,9=4,9
b: =1/3*7+3/4*18-2/3*20
=7/3+54/4-40/3
=-11+54/4
=2,5
c: =5/6*17-1/2*16+2/5*15
=85/6-8+6
=85/6-2
=73/6
d: =15*4/5+12*3/4-18*4/9
=12+9-8
=12+1=13
bài 9 :
6 mũ 2 x 73 + 36 x 3 mũ 3
197 -[ 6 x ( 5 - 1) mũ 2 +2022 mũ 0 ] : 5
bài 10: tìm số tự nhiên biết x
21- 4 . x = 13
30 : ( x - 3 ) + 1 = 4 mũ 5 : 4 mũ 3
( x - 1 ) mũ 3 + 5 . 6 = 38
Bài 9,
62x73+36x33=36x73+36x27=36(73+27)=36x100=3600.
197-\([\)6x(5-1)2+20220\(]\):5=197-\([\)6x16+1\(]\):5=197-97:5=197-97/5=888/5.
Bài 10,
21-4x=13
=>4x=21-13=8
=>x=8:4=2.
30:(x-3)+1=45:43=42=16
=>30:(x-3)=16-1=15
=>x-3=30:15=2
=>x=2+3=5.
(x-1)3+5x6=38
=>(x-1)3+30=38
=>(x-1)3=38-30=8=23
=>x-1=2
=>x=3.
1)Cho A=\(\frac{196}{197}\)+\(\frac{197}{198}\)
B=\(\frac{196+197}{197+198}\)
So sánh A và B
2)Cho B=\(\frac{1}{4}\)+\(\frac{1}{5}+\frac{1}{6}+\frac{1}{7}+...+\frac{1}{19}\).Chứng minh B>1
3)Tính nhanh
\(\frac{\frac{3}{5}+\frac{3}{7}-\frac{3}{11}}{\frac{4}{5}+\frac{4}{7}-\frac{4}{11}}\)
3)
3/5 + 3/7-3/11 / 4/5 + 4/7- 4/11
= 3.( 1/5 + 1/7 - 1/11)/4.(1/5+1/7-1/11)
= 3/4
1,
ta có B = 196+197/197+198 = 196/(197+198) + 197/(197+198)
196/197 > 196/197+198
197/198 > 197/197+198
=> A>B
C=1-2-3-4+5-6-7-8+...+197-198-199-200
C=(1-2-3-4)+(5-6-7-8)+...+(197-198-199-200)
=-8x50
=-400
Tìm hai biểu thức có giá trị bằng nhau:
a, 4 x 2145 d, (3+2) x 10287
b, 3964 x 6 e, (2100 + 45) x 4
c, 10287x 5 g, ( 4 + 2) x (3000 + 964 )
Dễ thấy \(4\times2145=\left(2100+45\right)\times4\\ 3964\times6=\left(4+2\right)\times\left(3000+964\right)\\ 10287\times5=\left(3+2\right)\times10287\)
Vậy a = e, b = g, c = d.
Tính nhanh (nếu có thể):
\(a,\frac{\frac{3}{41}-\frac{12}{47}+\frac{27}{53}}{\frac{4}{41}-\frac{16}{47}+\frac{36}{53}}+\frac{-0,25.\frac{-2}{3}-75\%:(\frac{-1}{2}+\frac{2}{3})}{|-1\frac{1}{2}|.(\frac{-2}{3}-0,75:\frac{3}{-2})}\)
\(b,A=158.(\frac{12-\frac{12}{7}-\frac{12}{289}-\frac{12}{85}}{4-\frac{4}{7}-\frac{4}{289}-\frac{4}{85}}:\frac{5+\frac{5}{13}+\frac{5}{169}+\frac{5}{91}}{6+\frac{6}{13}+\frac{6}{169}+\frac{6}{91}}).\frac{50550505}{711711711}\)
a: \(=\dfrac{3\left(\dfrac{1}{41}-\dfrac{4}{47}+\dfrac{9}{53}\right)}{4\left(\dfrac{1}{41}-\dfrac{4}{47}+\dfrac{9}{53}\right)}+\dfrac{-\dfrac{1}{4}\cdot\dfrac{-2}{3}-\dfrac{3}{4}:\dfrac{1}{6}}{\dfrac{3}{2}\cdot\left(\dfrac{-2}{3}-\dfrac{3}{4}\cdot\dfrac{-2}{3}\right)}\)
\(=\dfrac{3}{4}+\dfrac{\dfrac{2}{12}-\dfrac{9}{2}}{\dfrac{3}{2}\cdot\dfrac{-1}{6}}=\dfrac{3}{4}+\dfrac{-13}{3}:\dfrac{-3}{12}\)
\(=\dfrac{3}{4}+\dfrac{13}{3}\cdot\dfrac{12}{3}=\dfrac{3}{4}+\dfrac{156}{9}=\dfrac{217}{12}\)
b: \(A=158\left(\dfrac{12\left(1-\dfrac{1}{7}-\dfrac{1}{289}-\dfrac{1}{85}\right)}{4\left(1-\dfrac{1}{7}-\dfrac{1}{289}-\dfrac{1}{85}\right)}:\dfrac{5\left(1+\dfrac{1}{13}+\dfrac{1}{169}+\dfrac{1}{91}\right)}{6\left(1+\dfrac{1}{13}+\dfrac{1}{169}+\dfrac{1}{91}\right)}\right)\cdot\dfrac{50550505}{711711711}\)
\(=158\cdot\left(3\cdot\dfrac{6}{5}\right)\cdot\dfrac{50550505}{711711711}\)
\(\simeq40.39\)