1+2+3+4+5+.......+1020=??
a)1020+X.1/3=4/5+1020
b) X:2/3=25/1/2
c)5/4/9+X-7/7/18=15/3/4
1020+X.1/3=4/5+1020
\(1020+Xx\frac{1}{3}=\frac{4}{5}+1020\)
\(=1020+Xx\frac{1}{3}=\frac{5104}{5}\)
\(=Xx\frac{1}{3}=\frac{5104}{5}-1020\)
\(=Xx\frac{1}{3}=\frac{4}{5}\)
\(=\frac{4}{5}:\frac{1}{3}\)
\(=\frac{12}{5}\)
\(1020+x.\frac{1}{3}=\frac{4}{5}+1020\)
\(1020+x.\frac{1}{3}=\frac{5104}{5}\)
\(x.\frac{1}{3}=\frac{5104}{5}-1020\)
\(x.\frac{1}{3}=\frac{4}{5}\)
\(x=\frac{4}{5}:\frac{1}{3}\)
\(x=\frac{12}{5}\)
♥ ☼ ↕ ✿ ⊰ ⊱ ✪ ✣ ✤ ✥ ✦ ✧ ✩ ✫ ✬ ✭ ✯ ✰ ✱ ✲ ✳ ❃ ❂ ❁ ❀ ✿ ✶ ✴ ❄ ❉ ❋ ❖ ⊹⊱✿ ✿⊰⊹ ♧ ✿
\(1020+x\cdot\frac{1}{3}=\frac{4}{5}+1020\)
\(1020+x\cdot\frac{1}{3}=\frac{5104}{5}\)
\(x\cdot\frac{1}{3}=\frac{5104}{5}-1020\)
\(x\cdot\frac{1}{3}=\frac{4}{5}\)
\(x=\frac{4}{5}\div\frac{1}{3}\)
\(x=\frac{12}{5}\)
Bài 1 Tính tổng
1)1-2+3-4+5-6+...+1019-1020
2)(-1)+2+(-3)+4+...+(-99)+100
3)1-3+5-7+...+2017-2019+2020
4)2-4+6-8+...+48-50
5)1+2-3-4+...+97+98-99-100
Giúp mình nha , đang cần gấp
1)1-2+3-4+5-6+...+1019-1020 (có 1020 số hạng)
= (1-2+3-4) + (5-6+7-8) +.....+(1017-1018+1019-1020) (có 225 nhóm)
= -2 +(-2) +...........+(-2) ( có 225 số hạng)
= -2.225
= -450
5)1+2-3-4+...+97+98-99-100
= (1+2-3-4) +..........+(97+98-99-100)
= (-4) +..........(-4)
= (-4). 25
= -100
2)(-1)+2+(-3)+4+...+(-99)+100
= -1 +2 -3+4+.....-99+100
= (2-1) +(4-3) +....+(100-99) ( Có 50 cặp )
= 1+ 1+...+1 ( Có 50 số )
=1.50
=50
4) Nếu đổi +48 thành -48 thì mik làm đc
2-4+6-8+...-48-50
= 2+ (6-4) + (10-8) + ...+(50-48)
=2+2+2+....+2
=2.13
=26
81,6 : 6 1285:5 4911:3
1020:4
81,6:6 1285:5 4911:3 1020:4
\(81,6:6=13,6\)
\(1285:5=257\)
\(4911:3=1637\)
\(1020:4=255\)
a^2=?
Biet 1+2+3+4+...+k=a
va (k+1).(k-2)(k+3).(k-4)=1020
[(1+2019/1)+(1+2019/2)+...+(1+2019/1020)]:[(1+1020/1)(1+1020/2)+....+(1+1020/2019)]
Mik sắp nộp r ai nhanh mik tick liền lun miễn là bài làm tốt 👍
C.
24:{ 300:[ 350-( 175+25 )]× 1020 } D.
62: 2× 3 + 42× 79 - 23 × 5
c: \(24:\left\{300:\left[350-\left(175+25\right)\right]\cdot102\right\}\)
\(=\dfrac{24}{300:\left(350-200\right)\cdot102}\)
\(=\dfrac{24}{300:150\cdot102}=\dfrac{24}{204}=\dfrac{2}{17}\)
d: \(6:2\cdot3+4\cdot79-2\cdot5\)
\(=9-10+316\)
=316-1
=315
\(C)24:\left\{300:\left[350-\left(175+25\right)\right]\cdot102^0\right\}\)
\(=24:\left[300:\left(350-200\right)\cdot1\right]\)
\(=24:\left(300:150\right)\)
\(=24:2\)
\(=12\)
\(D)6^2:2\cdot3+4^2\cdot79-2^3\cdot5\)
\(=36:2\cdot3+16\cdot79-8\cdot5\)
\(=54+1264-40\)
\(=1278\)
Câu 1
2000-3000=
1000+200=
Câu 2
1020-1003=
33000+22000=
Câu 3
1000x9=
2400x3=
Câu 4
3000:6=
2000:5=
C1 2000-3000=-1000
1000+200=1200
C2 1020-1003=1017
33000+22000=55000
C3 1000X9 =9000
2400X3=7200
C4 3000:6=500
2000:5=4000