1) Tính bằng cách hợp lí nhất
a) 21x72-11x72+90x72+49x125x16
b) (2^2+2^1+2^2+2^3) .2^0.2^1.2^2.2^3
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z lm lại, nhưng nó cứ sao ý!
\(\left(2^2+2^1+2^2+2^3\right).2^0.2^1.2^2.2^3\)
\(=18.64\)
\(=1152\)
Sửa đề:
đặt A = \(\left(2^0+2^1+2^2+2^3\right).2^0.2^1.2^2.2^3\)
\(A=\left(1+2+2^2+2^3\right).2^6\)
\(A=2^6+2^7+2^8+2^9\)
\(\Rightarrow2A=2^7+2^8+2^9+2^{10}\)
\(\Rightarrow2A-A=2^{10}-2^6\)
\(A=2^{10}-2^6\)
\(A=960\)
xem đề mk ghi như z cs đúng ko?
(2^2 + 2^1 + 2^2 + 2^3). 2^0. 2^1. 2^2. 2^3
=(4 + 2 + 4 + 8). 1. 2. 4. 8
=18.64
=1152
\(C=2^0+2^1+2^2+2^3+2^0+2^1+2^2+2^3\)
\(=\left(2^0.2\right)+\left(2^1.2\right)+\left(2^2.2\right)+\left(2^3.2\right)\)
\(=2+4+8+16\)
\(=\left(2+8\right)+\left(4+16\right)\)
\(=10+20\)
\(=30\)
\(D=\left(2^0+2^1+2^2+2^3\right).2^0.2^1.2^2.2^3\)
\(=\left(1+2+4+8\right).1.2.4.8\)
\(=\left(8+2+4+1\right).1.2.4.8\)
\(=\left(10+4+1\right).1.2.4.8\)
\(=15.1.2.4.8\)
\(=\left(15.2\right).1.4.8\)
\(=30.1.4.8\)
\(=120.8\)
\(=960\)
Ta có F=(2^0+2^1+2^2+2^3).2^0.2^1.2^2.2^3
\(\Rightarrow F=\left(1+2+4+8\right).1.2.4.8\)
\(F=15.64\)
\(F=960\)
\(A=2^0.2^1.2^2....2^{100}\)
\(A=2^{0+1+2+...+100}\)
\(A=2^{101.50}\)
\(A=2^{5050}\)
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) 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