Question

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

Answer 1

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

Answer 2

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/ \(\left(-37\right).86+37.76\)

\(=37.\left(-86\right)+37.76\)

\(=37.\left(-86+76\right)\)

\(=37.\left(-10\right)\)

\(=-370\)