Bài 3: Tính nhanh:
a) 2,83.5,68-2,83.4,68+1,17.5,68-1,17.4,68
b) 1112-1372-482+96.137
Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
a: =-45*24+120
=-1080+120
=-960
b: =134(-1+51-48)
=134*2
=268
c: =-41*59-41*2+59*41-59*2
=-2(41+59)
=-200
a) 4 x 76 + 76 x 7
= (4 + 7) x 76
= 11 x 76
= 836
b) 4 x 54 + 54 x 2 + 5 x 54
= (4 + 4 + 5) x 54
= 13 x 54
= 702
c) 37 + 3 x 37 + 5 x 37 + 2 x 37
= 37 x (3 + 5 + 2)
= 37 x 10
= 370
a) 4 x 76 + 76 x 7
= (4 + 7) x 76
= 11 x 76
= 836
b) 4 x 54 + 54 x 2 + 5 x 54
= (4 + 4 + 5) x 54
= 13 x 54
= 702
c) 37 + 3 x 37 + 5 x 37 + 2 x 37
= 37 x (3 + 5 + 2)
= 37 x 10
= 370
Bài 1: Thực hiện phép tính:
\(\text{a, 1,3 + 2,5 – 4,7 + 5,6 – 4,3=}0,4\)
\(\text{b, - 5,7 + 4,2 – 8,2 + 11,7}=2\\ \)
\(\text{c, 25.(- 0,8).4.(-0,5).0,224}=8,96\)
Bài 2.
a) 1013 = (100+1)3 = 1003+3.1002.1+3.100.12+13
= 1000000+30000+300+1 = 1030301
b) 2993 = (300-1)3 = 3003-3.3002.1+3.300.12-13
= 27000000 - 270000 + 900 -1 = 26730899
c) 993 = (100-1)3 = 1003-3.1002.1+3.100.12-1
= 1000000 - 30000 + 300 -1 = 970299
\(1,\\ b,A=\left(u-v\right)^3+3uv\left(u+v\right)\\ A=u^3-3u^2v+3uv^2-v^3+3u^2v+3uv^2=u^3-v^3\\ c,6\left(c-d\right)\left(c+d\right)+2\left(c-d\right)^2-\left(c-d\right)^3\\ =6c^2-6d^2+2c^2-4cd+2d^2-c^3+3c^2d-3cd^2+d^3\\ =8c^2-c^3-4d^2-4cd+3c^2d-3cd^2+d^3\)
\(2,\\ a,101^3=\left(100+1\right)^3\\ =100^3+3\cdot10000\cdot1+3\cdot100\cdot1+1\\ =1000000+30000+300+1=1030301\\ b,299^3=\left(300-1\right)^3\\ =300^3-3\cdot90000\cdot1+3\cdot300\cdot1-1\\ =27000000-270000+900-1\\ =26730899\\ c,99^3=\left(100-1\right)^3\\ =100^3-3\cdot10000\cdot1+3\cdot100\cdot1-1\\ =1000000-30000+300-1=970299\)
a) 8,8 : 2,5 + 7,6 : 2,5 - 6,4 : 2,5
= (8,8 + 7,6 - 6,4) : 2,5
= 10 : 2,5
= 4
\(a.\)
\(8.8:2.5+7.6:2.5-6.4:2.5\)
\(=\left(8.8+7.6-6.4\right):2.5\)
\(=10:2.5\)
\(=4\)
\(b.\)
\(0.25\times1200+125\times1.5\times2-250\times2.6\)
\(=250\times1.2+250\times1.5-250\times2.6\)
\(=250\times\left(1.2+1.5-2.6\right)\)
\(=250\times0.1=25\)
\(c.\)
\(\left(32\times11-3200\times0.1-32\right):\left(81.6\times27.3-17.3\times81.6\right)\)
\(=\left[32\times\left(11-10-1\right)\right]:\left[81.6\times\left(27.3-17.3\right)\right]\)
\(=0\)
a) Ta có: \(A=\dfrac{37^3+12^3}{49}-37\cdot12\)
\(=\dfrac{\left(37+12\right)\left(37^2-37\cdot12+12^2\right)}{49}-37\cdot12\)
\(=37^2-2\cdot37\cdot12+12^2\)
\(=\left(37-12\right)^2\)
\(=25^2=625\)
a. A = (a + b)3 - (a - b)3
A = \(\left[\left(a+b\right)-\left(a-b\right)\right]\left[\left(a+b\right)^2+\left(a+b\right)\left(a-b\right)+\left(a-b\right)^2\right]\)
A = (a + b - a + b)\(\left[a^2+2ab+b^2+a^2-b^2+a^2-2ab+b^2\right]\)
A = 2b(a2 + a2 + a2 + 2ab - 2ab + b2 - b2 + b2)
A = 2b(3a2 + b2)
A = 6a2b + 2b3
a) 2,83.5,68-2,83.4,68+1,17.5,68-1,17.4,68
= 2,83.(5,86-4,86)+1,17.(5,86-4,86)=2,83.1+1,17.1=4
b) 1112-1372-482+96.137
= 1112-(1372-2.48.137+482)=1112-(137-48)2=1112-892=(111-89)(111+89)=22.200=4400
a) 2,83.5,68-2,83.4,68+1,17.5,68-1,17.4,68
= (2,83.5,68-2,83.4,68)+(1,17.5,68-1,17.4,68)
=2,83.(5,68-4,68)+1,17(5,68-4,68)=2,83+1,17=4