b: \(=128\left(-25-89+89-125\right)=128\cdot\left(-150\right)=-19200\)

a) 5 . 125 . 2 . 41 . 8

= (5 . 8) . (125 . 2) . 41

= 40 . 250 . 41

= 10 000 . 41

= 410 000

b) 25 . 7 . 10 . 4

= (25 . 4 ) . (10 . 7)

= 100 . 70

= 7000

Chúc bạn học tốt!! ^^

a,5.125.2.41.8=(125.8).(2.5).41=1000.10.41=410000

b,25.7.10.4=(25.4).70=100.70=7000

c,8.12.125.2=(8.125).12.2=100.24=2400

d,4.36.25.50=(4.25).(2.50).18=100.100.18=180000

c) 8 . 12 . 125

= (125 . 8) . 12

= 1000 . 12

= 12 000

d) 4 . 36 . 25 . 50

= (25 . 4) . (50 . 36)

= 100 . 1800

= 180 000

Chúc bạn học tốt!! ^^

a)= \(2^3\left(17-14\right)\)

\(=8.3\)

\(=24\)

b)\(=17\left(85+15\right)-120\)

\(=17.100-120\)

\(=1700-120\)

\(=1580\)

c)\(=\left(25.4\right).\left(125.8\right).\left(2.5\right)\)

\(=100.1000.10\)

\(=1000000\)

d)\(=24.53+24.87-24.40\)

\(=24\left(53+87-40\right)\)

\(=24.100\)

\(=2400\)

e)\(=5.7.77-7.60-7.7.25-15.6.7\)

\(=7\left(5.77-60-7.25-15.6\right)\)

\(=7\left(385-60-175-90\right)\)

\(=7.60\)

\(=420\)

a) 145 + 43 + (-145) + 57

= [145 + (-145)] + [43 + 57]

= 0 + 100

= 100

A) = (145+(-145))+(43+57)

= 0 + 100

= 100

Bài 2: Tính một cách hợp lý:

a) 145 + 43 + (– 145) + 57;

= 145 - 145 + 43 + 57 = 0 + 100 = 100

b) (– 213) + 36 + (– 787) + 64;

= -213 - 787 + 36 + 64 = -1000 + 100 = -900

c) (– 2) + (– 4) + (– 6) + (– 10) + 8 + 10 + 12;

= -2 +12 - 4 - 6 - 10 + 10 + 8 = 10 - 10 -10 + 10 + 8 = 8 

d) (– 2 020) + (– 598) + (– 201) + 498 + 301.

= -2020 - 799 + 799 = -2020

a, \(7^{2019}=7^3.7^{2016}=343.\left(7^4\right)^{504}=343.\left(...1\right)^{504}=343.\left(...1\right)=\left(....3\right)\)

b, \(12^{2019}=12^3.12^{2016}=\left(...8\right).\left(12^4\right)^{504}=\left(...8\right).\left(...6\right)^{504}=\left(...8\right).\left(...6\right)=\left(...8\right)\)

c, \(11^8+12^8+13^8+14^8+15^8+16^8\)

\(=\left(...1\right)+\left(12^4\right)^2+\left(13^4\right)^2+\left(...5\right)+\left(...6\right)=\left(....1\right)+\left(....6\right)^2+\left(...1\right)^2+\left(...5\right)+\left(...6\right)\)

\(=\left(....1\right)+\left(....6\right)+\left(...1\right)+\left(...5\right)+\left(...6\right)=\left(...9\right)\)

d, \(11^{123}+13^{124}+15^{125}=\left(....1\right)+\left(13^4\right)^{31}+\left(....5\right)=\left(...1\right)+\left(...1\right)+\left(....5\right)=\left(...7\right)\)

\(a,7^{2019}=\left[7^3\right]^{673}=\overline{....}3^{673}=\overline{....3}\)

Vậy chữ số tận cùng của 7²⁰¹⁹ là 3

\(b,12^{2019}=\left[12^3\right]^{673}=\overline{....8}^{673}=\overline{....8}\)

Vậy chữ số tận cùng của 12²⁰¹⁹ là 8

Làm nốt

a: =-26+56=30

e: =-125+48+125-53=-5

a) (-125) . 4

= -500

b) (-2017) . (-2016) . 0

= 0

c) (-12) . (-11)

= 132

d) (-4) . (-8) . (-25) . (-125)

= [(-4).(-25)].[(-8).(-125)]

= 100.1000

= 100000

e) (-2).(-5).(-7)

= [(-2).(-5)].(-7)

= 10.(-7)

= -70

a: \(\left(-125\right)\cdot4=-\left(125\cdot4\right)=-500\)

b: \(\left(-2017\right)\cdot\left(-2016\right)\cdot0=0\cdot2016\cdot2017=0\)

c: \(\left(-12\right)\cdot\left(-11\right)=12\cdot11=12\cdot10+12=120+12=132\)

d: \(\left(-4\right)\cdot\left(-8\right)\cdot\left(-25\right)\cdot\left(-125\right)\)

\(=4\cdot8\cdot25\cdot125\)

\(=4\cdot25\cdot8\cdot125\)

\(=100\cdot1000=100000\)

e: \(\left(-2\right)\cdot\left(-5\right)\cdot\left(-7\right)\)

\(=-7\cdot2\cdot5\)

\(=-7\cdot10=-70\)

A = (2 + 2²) + (2³ + 2⁴ ) +…(2¹⁹⁹ + 2²⁰⁰)

A = 6 + 2² (2 + 2² ) +… + 2¹⁹⁸ (2 + 2²)

A = 6 + 2² (6 ) +… + 2¹⁹⁸ (6)

A = 6(1 + 2² +… + 2¹⁹⁸)

Vậy A chia hết cho 6

a) \(\left(\frac{2}{7}+\frac{3}{8}+\frac{12}{7}+\frac{5}{8}\right).\frac{19}{36}\)

\(=\left\{\left(\frac{2}{7}+\frac{12}{7}\right)+\left(\frac{3}{8}+\frac{5}{8}\right)\right\}.\frac{19}{36}\)

\(=\left(\frac{14}{7}+\frac{8}{8}\right).\frac{19}{36}\)

\(=\left(2+1\right).\frac{19}{36}\)

\(3.\frac{19}{36}=\frac{19}{12}\)