Bài 1: Tính hợp lý (nếu có thể)

a) 5.(-8).(-2).(-3)\(=\left(-2.5\right).\left(\left(-3\right).\left(-8\right)\right)=-10.24=-240\)

c) 147.333+233.(-147)\(=147\left(333-233\right)=147.100=14700\)

b) (-125).8.(-2).5.19\(=\left(-125.8\right).\left(-2.5\right).19=-1000.\left(-10\right).19=190\text{ }000\)

d) (-115).27+33.(-115)\(=-115.\left(27+33\right)=-115.60=-6900\)

Bài 2: Tìm số nguyên x, biết: 

a) 2x+19=15\(\Leftrightarrow2x=15-19=-4\Leftrightarrow x=-2\)

c) 24-(x-3)^3=-3\(\Leftrightarrow\left(x-3\right)^3=27=3^3\Leftrightarrow x-3=3\Leftrightarrow x=6\)

c=1+2+4+8+64

=79

\(C=2^0+2^1+2^2+2^3+2^0+2^1+2^2+2^3\)

\(=\left(2^0.2\right)+\left(2^1.2\right)+\left(2^2.2\right)+\left(2^3.2\right)\)

\(=2+4+8+16\)

\(=\left(2+8\right)+\left(4+16\right)\)

\(=10+20\)

\(=30\)

\(D=\left(2^0+2^1+2^2+2^3\right).2^0.2^1.2^2.2^3\)

\(=\left(1+2+4+8\right).1.2.4.8\)

\(=\left(8+2+4+1\right).1.2.4.8\)

\(=\left(10+4+1\right).1.2.4.8\)

\(=15.1.2.4.8\)

\(=\left(15.2\right).1.4.8\)

\(=30.1.4.8\)

\(=120.8\)

\(=960\)

Tính hop ly

21.49-11.49+90.49+49.125.16

= 49.( 21 - 11 + 90 + 125 . 16 )

= 49 . ( 10 + 90 + 2000 )

= 49 . 2100

= 102900

(2²+2¹+2²+2³).2⁰.2¹.2².2³

= ( 4 + 2 + 4 + 8 ) . 1 . 2 . 4 . 8

= 18 . 64

= 1152

Study well 

\(21.49-11.49+90.49+49.125.16\)

\(=49.\left(21-11+90+125.16\right)\)

\(=49.\left(10+90+2000\right)=49.2100\)

\(=102900\)

a. ta có \(2019.\left(-2\right)< 0\)

b. \(\left(-2018\right).\left(-2019\right)>0\)

c. \(\left(-1\right).\left(-2\right)\left(-3\right)..\left(-2020\right)>0\)

a) 21x7²-11x7²+90x7²+49x125x16

= 21 x 49 - 11 x 49 + 90 x 49 + 49 x 125 x 16

= 49 x ( 21 - 11 + 90 + 125 x 16 )

= 49 x ( 21 - 11 + 90 + 2000 )

= 49 x 2100

= ( 50 - 1 ) x 2100

= 50 x 2100 - 2100

= 105 000 - 2100

= 102 900

b) (2²+2¹+2²+2³) . 2⁰.2¹.2².2³

= ( 4 + 2 + 4 + 8 ) . 1 . 2 . 4 . 8

= 18 . 8 . 8

= 144 . 8

= 1152