37 + 45 + 46
BT2: Tính nhanh:
5) \(\dfrac{15}{7}\left(\dfrac{1}{5}-\dfrac{46}{45}\right)+\dfrac{46}{45}\left(\dfrac{15}{7}-\dfrac{45}{46}\right)\)
6) \(\dfrac{43}{47}\left(\dfrac{18}{37}+\dfrac{47}{43}\right)-\dfrac{18}{37}\left(\dfrac{43}{47}+\dfrac{37}{36}\right)\)
1/Ta co :
\(\dfrac{15}{7}.\left(\dfrac{1}{5}-\dfrac{46}{45}\right)+\dfrac{46}{45}.\left(\dfrac{15}{7}-\dfrac{45}{46}\right)\)
=\(\dfrac{15}{7}.\dfrac{1}{5}-\dfrac{15}{7}.\dfrac{46}{45}+\dfrac{46}{45}.\dfrac{15}{7}-\dfrac{46}{45}.\dfrac{45}{46}\)
=\(\dfrac{15}{7}.\left(\dfrac{1}{5}-\dfrac{46}{45}+\dfrac{46}{45}\right)-1\)
=\(\dfrac{15}{7}.\dfrac{1}{5}-1\)
=\(\dfrac{3}{7}-1=\dfrac{-4}{7}\)
2/Ta co
\(\dfrac{43}{47}.\left(\dfrac{18}{37}+\dfrac{47}{43}\right)-\dfrac{18}{3}.\left(\dfrac{43}{47}+\dfrac{37}{36}\right)\)
=\(\dfrac{43}{47}.\dfrac{18}{37}+\dfrac{43}{47}.\dfrac{47}{43}-\dfrac{18}{37}.\dfrac{43}{47}+\dfrac{18}{37}.\dfrac{37}{36}\)
=\(\dfrac{18}{37}.\left(\dfrac{43}{37}-\dfrac{43}{37}+\dfrac{37}{36}\right)+1\)
=\(\dfrac{18}{37}.\dfrac{37}{36}+1\)
=\(\dfrac{1}{2}+1=\dfrac{3}{2}\)
tick cho mk nha
Thực hiện phép tính
3 7 + 4 5 = 6 5 - 4 6 = 3 4 × 5 = 3 4 =
Đặt tính rồi tính:
a) 46 + 37
b) 92 - 45
c) 38 + 12
d) 78 – 29
HT
phuonglebao9@gmail.com
Tính nhanh
a, 27×121-87×27-27×(-16)
b, 17×(-37)-23×37-46×(-37)
c, 41×(-18)+41×(-81)-41
d, 45×(-24)+(-10)×(-12)
MN CHO MIK XIN LỜI GIẢI CHI TIẾT NHÉ
XIN CẢM ƠN
a. 27 x (121-87-(16))
= 27 x 50
= 1350
b. (-37)x (17+23-46)
=-37 x -6
= 222
c. 41 x (-18-81-1)
= 41 x -100
= -4100
d. 1080 + 120
= 1200
Tính nhanh: A=4/3+7/6+11/10+16/15+22/21+29/28+37/36+46/45
A=4/3+7/6+11/10+16/15+22/21+29/28+37/36+46/45
A = ( 1 + 1/3 ) + ( 1 + 1/6 ) + ( 1 + 1/10 ) + ( 1 + 1/15 ) + ( 1 + 1/21 ) + ( 1 + 1/28 ) + ( 1 + 1/36 ) + ( 1 + 1/45 )
A = ( 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 ) + - ( 1/3 + 1/6 + 1/10 + 1/15 + 1/21 + 1/28 + 1/36 + 1/45 )
A = 8 + 4/5
A = 44/5
A = 4/3 + 7/6 + 11/10 + 16/15 + 22/21 + 29/28 + 37/36 + 46/45
A = ( 1 + 1/3 ) + ( 1 + 1/6 ) + ( 1 + 1/10 ) + ( 1 + 1/15 ) + ( 1 + 1/21 ) + ( 1 + 1/28 ) + ( 1 + 1/36 ) + ( 1 + 1/45 )
A = ( 1 + 1 + 1 + ... + 1 ) - ( 1/3 + 1/6 + 1/10 + 1/15 + 1/21 + 1/28 + 1/36 + 1/45 )
Tính nhanh :
a. 37 . 15 + 15 . 63 + 17 . 4
b. 43 + 44+45+46 , + .............. +71 + 72
a.37.15+15.63+17.4
=15.(63+37)+(17.4)
=15.100+68
=1500+68
=1500
b.43+44+45+46+......+71+72
tổng trên có số số hạng là: (72-43)+1=30
tổng trên là: (72+43).30:2=1725
Tính nhanh: A=4/3+7/6+11/10+16/15+22/21+29/28+37/36+46/45
a, B= 263^2 + 74.263 + 37^2
b , C = 136^2 - 92.136;+ 46^2
c , D = ( 50^2 + 48^2 + 46^2 +....+ 2^2 ) - ( 49^2 + 47^2 + 45^2 + ...... + 1^2 )
Tính hợp lý
B=263^2+74.263+37^2
C=136^2-92.136+46^2
D=(50^2+48^2+46^2+....+2^2) - (49^2+47^2+45^2 +.........+ 1^2 )