Tính.
23 + 27 + 1 45 + 45 + 25 8 + 12 + 3 69 + 11 + 4
1+2+3+45+6+7+8++10+11+12+13+14+15+16+17+18+19+20+21+22+23+24+25+26+27+28+29+30=
Ai trả lời đúng mình tích cho
Nhớ tính thuận tiện nha
Lời giải:
$1+2+3+....+25$
$=(1+25)+(2+24)+(3+23)+(4+22)+(5+21)+(6+20)+(7+19)+(8+18)+(9+17)+(10+16)+(11+15)+(12+14)+13$
$=\underbrace{26+26+26+...+26}_{12}+13$
$=26\times 12+13=325$
a 12 – 34 b 23 – 47 c 31 – 23 d 9 – 5 e 4 – 15 25 f 23 13 17 57 g 4 . 9 6 . 12 – 7 h 14 6 19 14 19 i 56 – 8. 27 7 j 8 5 . 2 – 3 6 k 4 . 3 125 . 25 8 l 9 6 . 3 – 4 7 m 45. 18 – 15 – 18. 45 – 15
Tách từng câu ra giùm, như này ai giải nổi:)))))
1+2+3+4+5+6+7+8+9+10+11+12+13+14+15+16+17+18+19+20+21+22+23+24+25+26+27+28+29+30+31+32+33+34+35+36+37+38+39+40+41+42+43+44+45+46+47+48+49+50+51+52+53+54+56+57+58+59+60+61+62+63+64+65+66+67+68+69+70=?
bỏ dấu ngoặc rồi tính:
1)(38-42+14)-(25-27-15)
2)(12+21)-(23-21+10)
3)(57-725)-(605-53)
4)(55+45+15)-(15-55+45)
\(1,=38-42+14-25+27+15=27\)
\(2,=12+21-23+21-10=21\)
\(3,=57-725-605+53=-1220\)
\(4,=55+45+15-15+55-45=110\)
\(\text{1.(38-42+14)-(25-27-15)}\\ =38-42+14-25+27+15\\ =-4-11+42\\ =27\)
\(\text{2.(12+21)-(23-21+10)}\\ =12+21-23+21-10\\ =33+44-10=67\)
1,=38−42+14−25+27+15=271,=38−42+14−25+27+15=27
2,=12+21−23+21−10=212,=12+21−23+21−10=21
3,=57−725−605+53=−12203,=57−725−605+53=−1220
4,=55+45+15−15+55−45=110
Giải phương trình:
1) (3x-1)^2-5(2x+1)^2+96x-3)(2x+1)=(x-1)^2
2) (x+2)^3-(x-2)^3=12(x-1)-8
3) x-1/4-5-2x/9=3x-2/3
4) 25x-655/95-5(x-12)/209=[89-3x-2(x-13)/5]/11
5) 29-x/21+27-x/23+25-x/25+23-x/27=-4
6) x-69/30+x-67/32=x-63/36+x-61/38
7)x+117/19+x+4/28+x+3/57=0
8) 59-x/41+57-x/43+2=x-55?45+x-53/47-2
9) Cho phương trình: mx+x-m^2=2x-2 (x là ẩn). Tìm m để phương trình:
a) Có nghiệm duy nhất
b) Vô số nghiệm
c) Vô nghiệm
a) 21/47 + 9/45 +26/47 + 4/5
= (21/47 + 26/47) + (9/45 + 4/5)
=1+1 = 2
b) 15/12 + 5/13 - 3/12 - 18/13
= (15/12 - 3/12) + (18/13 - 5/13)
=1+1 = 2
c) 13/25 + 6/41 - 38/25 + 35/41 - 1/2
= (38/25 - 13/25) + (35/41 + 6/41) + 1/2
= 1+1 + 1/2 = 5/2
d) 27/23 + 5/21 - 4/23 + 6/21 + 1/2
= (27/23 - 4/23) + (6/21 - 5/21) + 1/2
= ..........................
Đúng không? Phần sau mình tính sao ra kết quả lạ lắm, tính giúp mình.
(-3/4+2/3):5/11+(-1/4+1/3):5/11
a)|x-13|-35-45=-47
b)(4+x).(x+3)=0
c)25-(5-x)=120-(28-5)
Tính:
1. 7 15 + 4 5 =
2. 4 5 × 5 8 =
3. 2 3 − 3 8 =
4. 1 2 : 2 5 =
ko xem dc de ban oi :/
2 . 53 . 27 + 6 . 9 . 87 - 3 . 18 . 40 = ???
12 . 25 + 29 . 25 + 59 . 25 = ???
43 . 37 + 93 . 43 + 57 . 61 + 69 . 57 = ???
12 . 53 + 53 . 172 - 53 = ???
35 . 54 + 35 . 58 + 65 . 75 + 65 . 45 = ???
39 . 8 + 70 . 3 + 31 . 8 = ???
2 . 53 . 27 + 6 . 9 . 87 - 3 . 18 . 40
= 2. 53 . 9 . 3 + 2. 3 .9 .87 - 3 .2 .9 .40
= 54.53+54.87-54.40
=54(53+87-40)
=54. 100=5400
12 . 25 + 29 . 25 + 59 . 25
= 25 . ( 12+29+59)
=25 . 90
=2250
43 . 37 + 93 . 43 + 57 . 61 + 69 . 57
= 43.(37+93)+57(61+69)
=43.130+57.130
=130.(43+57)
=130.100
=13 000
12 . 53 + 53 . 172 - 53
=53(12+172-1)
=53.184
=9752
35 . 54 + 35 . 58 + 65 . 75 + 65 . 45
=35(54+58)+65(75+45)
=35.112+65.120
=3920+7800
=11720
39 . 8 + 70 . 3 + 31 . 8
=8(39+31)+70.3
=8.70+70.3
=70.(8+3)
=70.11
=770
2 . 53 . 27 + 6 . 9 . 87 - 3 . 18 . 40
= ( 2 . 27 ) . 53 + ( 6 . 9 ) . 87 - ( 3 . 18 ) . 40
= 54 . 53 + 54 . 87 - 54 . 40
= 54(53+87-40)
= 5400
12 . 25 + 29 . 25 + 59 . 25
= 25( 12 + 29 + 59 )
= 2500
43 . 37 + 93 . 43 + 57 . 61 + 69 . 57
= 43( 37 + 93 ) + 57(61 + 69 )
= 5590 + 7410
= 13000
12 . 53 + 53 . 172 - 53
= 53( 12 + 172 ) - 53
= 9752 - 53
= 9699
35 . 54 + 35 . 58 + 65 . 75 + 65 . 45
= 35( 54 + 58 ) + 65( 75 + 45 )
= 3920 + 7800
= 11720