Tính hợp lí:\(4^2.102-4^3.17-4^2.34\)
Thuc hien phep tinh
a) 132(116-(132-128)^2)
b)4^2.102-4^3.17-4^2.34
c)7^3.9+3^2.7^4-4^5.539
d)2^3.5^2+75.2^3-100.7
Giải hộ mình nha
4^2.120-4^3.17+4^2.34
42.120-43.17+42.34
=42.120-42.4.17+42.34
=42.120-42.68+42.34
=42.(120-68+34)
=16.86
=1376
=42.120-42.41.17+42.34
=42.120-42.68+42.34
=42.(120-68+34)
=16.86
1376
Dấu chấm là nhân đấy các bạn "..''
a) 101-102-(-103)-104-(-105)-106-(-107)-108-(-109)-110
b) 5^3.[7+(-2)^3+(-2)^2]
c) 6.(-2)^3+5.(-4)-(-12)
d) (-4)^2.102-4^3.17-4^2.3^4
Tính hợp lí:
\(\dfrac{-4}{1.2}+\dfrac{-4}{2.3}+\dfrac{-4}{3.4}+...+\dfrac{-4}{97.98}+\dfrac{-4}{98.99}\)
Tính hợp lí:
(2^39 + 2^35) / (2^33 . 4)
(4^17 + 4^3) / (4^16 + 4^2)
\(\dfrac{2^{39}+2^{35}}{2^{33}\cdot4}\)
\(=\dfrac{2^{35}\cdot\left(2^4+1\right)}{2^{33}\cdot2^2}\)
\(=\dfrac{2^{35}\cdot\left(16+1\right)}{2^{35}}\)
\(=17\)
\(---\)
\(\dfrac{4^{17}+4^3}{4^{16}+4^2}\)
\(=\dfrac{4^3\cdot\left(4^{14}+1\right)}{4^2\cdot\left(4^{14}+1\right)}\)
\(=4\)
#\(Toru\)
Bài 3:Dùng tính chất phân phối của phép nhân và phép cộng để tính:
1.5(-3+2)-7.(5-4)
2.3.(-5+6)-4.(3-2)
3.17.(-84)+17.(-16)
4.1975.(-115)+1975.15
5.-145.(13-57)+57.(10-145)
6.157.17-157.7
7.199.(15-17)-199.(-17+5)
8.-39.(5-99)+99.(10-39)
9.-38.(25-4)+25.(-4+38)
10.(-37).86+37.76
1: =-3x5+2x5-7x5+7x4=-8x5+7x4=-40+28=-12
2: =-3x5+3x6-4x3+4x2=-9+8=-1
3: =17(-84-16)=-1700
4: =1975(-115+15)=-197500
5: =-145x13+145x57+57x10-57x145=-1315
1/ \(5\left(-3+2\right)-7\left(5-4\right)\)
\(=5.\left(-3\right)+5.2-7.5-7.\left(-4\right)\)
\(=-15+10-35+28\)
\(=-5-7\)
\(=-12\)
2/ \(3.\left(-5+6\right)-4.\left(3-2\right)\)
\(=3.\left(-5\right)+3.6-4.3-4.\left(-2\right)\)
\(=-15+18-12+8\)
\(=3-4\)
\(=-1\)
3/ \(17.\left(-84\right)+17.\left(-16\right)\)
\(=17.\left(-84-16\right)\)
\(=17.\left(-100\right)\)
\(=-1700\)
4/ \(1975.\left(-115\right)+1975.15\)
\(=1975.\left(-115+15\right)\)
\(=1975.\left(-100\right)\)
\(=-197500\)
5/ \(-145.\left(13-57\right)+57.\left(10-145\right)\)
\(=-145.13-145.\left(-57\right)+57.10+57.\left(-145\right)\)
\(=-145.\left(-57+57\right)-145.13+57.10\)
\(=0-1885+570\)
\(=-1315\)
6/ \(157.17-157.7\)
\(=157.\left(17-7\right)\)
\(=157.10\)
\(=1570\)
7/ \(199.\left(15-17\right)-199.\left(-17+5\right)\)
\(=199.\left(-2\right)-199.\left(-12\right)\)
\(=199.\left(-2\right)+199.12\)
\(=199.\left(-2+12\right)\)
\(=199.10\)
\(=1990\)
8/ \(-39.\left(5-99\right)+99.\left(10-39\right)\)
\(=-39.5-39.\left(-99\right)+99.10+99.\left(-39\right)\)
\(=-39.\left(-99+99\right)-39.5+99.10\)
\(=0-195+990\)
\(=795\)
9/ \(-38.\left(25-4\right)+25.\left(-4+38\right)\)
\(=-38.25-38.\left(-4\right)+25.\left(-4\right)+25.38\)
\(=25.\left(-38+38\right)-4.\left(-38+25\right)\)
\(=0-4.\left(-13\right)\)
\(=52\)
10/ \(\left(-37\right).86+37.76\)
\(=37.\left(-86\right)+37.76\)
\(=37.\left(-86+76\right)\)
\(=37.\left(-10\right)\)
\(=-370\)
Tính hợp lí
A = 4/4.7 + 4/7.10 + ...... + 4/79.82
\(4\left(\frac{1}{4.7}+\frac{1}{7.10}+...+\frac{1}{79.82}\right)\)
\(=\frac{4}{3}\left(\frac{3}{4.7}+\frac{3}{7.10}+...+\frac{3}{79.8}\right)\)
\(=\frac{4}{3}\left(\frac{1}{4}-\frac{1}{7}+\frac{1}{7}-\frac{1}{10}+...+\frac{1}{79}-\frac{1}{82}\right)\)
\(=\frac{4}{3}\left(\frac{1}{4}-\frac{1}{82}\right)\)
\(=\frac{4}{3}.\frac{39}{164}=\frac{13}{41}\)
tính tổng sau bằng cách hợp lí : C=4+4 2+4 3+...+ 4 n
Tính hợp lí: C = (1/23-4/23.25) .(1-4/36) . (1-4/49)...(1-4/625)