tinh nhanh 108*100+94*200/74*76+252*38
tinh nhanh 100-44+50-54+60-64+70-74+80-84+90-94.Giup minh voi
THUC HIEN PHEP TINH ( TINH NHANH NEU CO THE ) :
1) ( 56 x 46 - 25 x 23 ) : 23
2) ( 28 x 54 + 56 x 36 ) : 21 : 2
3) ( 76 x 34 - 19 x 64 ) : ( 38 x 9 )
4) ( 2 + 4 + 6 + .... + 100 ) x ( 36 x 333 - 108 x 111 )
5) ( 5x 411 - 3 x 165 ) : 410
6) 7256 x 4375 - 725
3650 + 4375 x 7255
Tính nhanh
71+72+73+74+75+76+77+78+79
tìm x
X x 7 +X x 2 = 108
71 + 72 + 73 + 74 + 75 + 76 + 77 + 78 + 79
= ( 71 + 79 ) + ( 72 + 78 ) + ( 73 + 77 ) + ( 74 + 76 ) + 75
= 150 + 150 + 150 + 150 + 75
= 150 x 4 + 75
= 600 + 75
= 675
Tìm x :
X x 7 + X x 2 = 108
X x ( 7 + 2 ) = 108
X x 9 = 108
X = 108 : 9
X = 12
\(71+72+73+74+75+76+77+78+79\)
\(=\left(71+79\right)+\left(72+78\right)+\left(73+77\right)+\left(74+76\right)+75\)
\(=150+150+150+150+75\)
\(=600+75\)
\(=675\)
\(X\)x\(7+X\)x\(2=108\)
\(X\)x\(\left(7+2\right)=108\)
\(X\)x\(9=108\)
\(X=108:9\)
\(X=12\)
Vậy \(X=12\)
\(71+72+73+74+75+76+77+78+79\)
\(=\left(71+79\right)+\left(72+78\right)+\left(73+77\right)+\left(74+76\right)+75\)
\(=150+150+150+150+75\)
\(=150.4+75=600+75=675\)
\(7x+2x=108\Leftrightarrow x\left(7+2\right)=108\Leftrightarrow9x=108\)
\(\Leftrightarrow x=108:9\Leftrightarrow x=12\)
tinh nhanh
24+42+38+58+76+62
(24+76)+(42+58)+(38+62)=100+100+100=300
24+42+38+58+76+62=(24+76)+(42+58)+(38+62)
=100+100+100
=300
\(24+42+38+58+76+62\)
\(=\left(24+76\right)+\left(42+58\right)+\left(38+62\right)\)
\(=100+100+100\)
\(=300\)
15/37x(38/41-74/45)-38/41x(15/37+82/76)
\(=\dfrac{15}{37}\cdot\dfrac{38}{41}-\dfrac{15}{37}\cdot\dfrac{74}{45}-\dfrac{38}{41}\cdot\dfrac{15}{37}-\dfrac{38}{41}\cdot\dfrac{82}{76}\)
\(=\dfrac{-1}{3}\cdot2-\dfrac{1}{2}\cdot2=-\dfrac{2}{3}-1=-\dfrac{5}{3}\)
không thực hiện phép tính hãy so sánh các tổng sau
32+74+96+18+50
90+36+1+54+78
10+52+76+94+38
98+14+30+72+56
sao lại không thực hiện phép tính chứ ?
các tổng đều bằng nhau
32+74+96+18+50=90+36+12+54+78=10+52+76+94+38=98+14+30+72+56
tính nhanh
\(\dfrac{76}{34}+\dfrac{98}{100}+\dfrac{38}{17}+\dfrac{49}{50}\)
76/34+98/100+38/17+49/50
= 76/34+98/100+76/34+98/100
=( 76/34+76/34)+ (98/100+98/100)
=152/34+196/100
= 2733/425
ht
1)co bao nhieu so tu nhien co ba chu so la ba so tu nhien lien tiep tu nho den lon neu viet so ay theo thu tu nguoc lai cua cac chu so ay theo thu tu nguoc lai cua cac chu so thi so moi hon so cu la bao nhieu?
tinh nhanh:
a)100-94+90-84+80-74+70-64+60-54
b)5.125.20.16
c)36.(140+97)+73.(232+68)
d)5+9+13+...+2005+2009+2013
e)3+6+9+...+108
f)1+2+4+8+...+4098
74 * 76 -196 / 72 * 74 + 100