Tính giá trị biểu thức:
A=(4^5×9^4+2×6^9):(2^10×3^8-6^8×2)
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a) Có x = 2020 => x + 1 = 2021. Thay 2021 = x + 1 vào A
\(A=x^6-\left(x+1\right)^5+\left(x+1\right)x^4-\left(x+1\right)x^3+\left(x+1\right)x^2-\left(x+1\right)x+x+1\)
\(A=x^6-x^6-x^5+x^5+x^4-x^4-x^3+x^3+x^2-x^2-x+x+1\)
\(A=1\)
b) Có x = -19 => x - 1 = -20 => - ( x - 1 ) = 20. Thay 20 = - ( x - 1) vào B
\(B=x^{10}-\left(x-1\right)x^9-\left(x-1\right)x^8-\left(x-1\right)x^7-...-\left(x-1\right)x^2-\left(x-1\right)x-x+1\)
\(B=x^{10}-x^{10}+x^9-x^9+...+x^2-x^2+x-x+1\)
\(B=1\)
Chúc bạn học tốt!!!
a/\(\frac{4^5.9^4-2.6^9}{2^{10}.3^8+6^8.20}=\frac{\left(2^2\right)^5.\left(3^2\right)^4-2.\left(2.3\right)^9}{2^{10}.3^8+\left(2.3\right)^8.2^2.5}\)
= \(\frac{2^{10}.3^8-2.2^9.3^9}{2^{10}.3^8+2^8.3^8.2^2.5}=\frac{2^{10}.3^8-2^{10}.3^9}{2^{10}.3^8+2^{10}.3^8.5}=\frac{2^{10}.3^8.\left(1-3\right)}{2^{10}.3^8\left(1+5\right)}=\frac{1-3}{1+5}=\frac{-2}{6}=-3\)
A)\(\dfrac{7}{20}-\left(\dfrac{5}{8}-\dfrac{2}{5}\right)\)
\(=\dfrac{7}{20}-\left(\dfrac{25}{40}-\dfrac{16}{40}\right)\)
\(=\dfrac{7}{20}-\dfrac{9}{40}\)
\(=\dfrac{14}{40}-\dfrac{9}{40}=\dfrac{5}{40}=\dfrac{1}{8}\)
B) \(\dfrac{5}{6}+\left(\dfrac{5}{9}-\dfrac{1}{4}\right)\)
\(=\dfrac{5}{6}+\left(\dfrac{20}{36}-\dfrac{9}{36}\right)\)
\(=\dfrac{5}{6}+\dfrac{11}{36}\).
\(=\dfrac{30}{36}+\dfrac{11}{36}=\dfrac{41}{36}\)
C) \(\dfrac{9}{10}-\left(\dfrac{2}{5}-\dfrac{3}{10}\right)+\dfrac{7}{20}\)
\(=\dfrac{9}{10}-\left(\dfrac{4}{10}-\dfrac{3}{10}\right)+\dfrac{7}{20}\)
\(=\dfrac{9}{10}-\dfrac{1}{10}+\dfrac{7}{20}\)
\(=\dfrac{18}{20}-\dfrac{2}{20}+\dfrac{7}{20}=\dfrac{23}{20}\)
a: =7/20-5/8+2/5
=14/40-25/40+16/40
=5/40=1/8
b: =5/6+5/9-1/4
=30/36+20/36-9/36
=41/36
c: =9/10-2/5+3/10+7/20
=12/10-2/5+7/20
=7/20+6/5-2/5
=7/20+4/5
=7/20+16/20
=23/20
|(5/8-5/14)+(3/8-9/14)|:4/7
=|(5/8+3/8)+(-5/14-9/14)|:4/7
=|1+(-1)|:4/7
=0
đáp án 194
\(A=\left(4^5\times9^4+2\times6^9\right)\div\left(2^{10}\times3^8-6^8\times2\right)\)
\(\Leftrightarrow A=\frac{4^5\times9^4+2\times6^9}{2^{10}\times3^8-6^8\times2}\)
\(\Leftrightarrow A=\frac{\left(2^2\right)^5\times\left(3^2\right)^4+2\times\left(3\times2\right)^9}{2^{10}\times3^8-\left(3\times2\right)^8\times2}\)
\(\Leftrightarrow A=\frac{2^{10}\times3^8+2\times3^9\times2^9}{2^{10}\times3^8-3^8\times2^8\times2}\)
\(\Leftrightarrow A=\frac{2^{10}\times3^8+2^{10}\times3^8\times3}{2^{10}\times3^8-3^8\times2^9}\)
\(\Leftrightarrow A=\frac{3^8\left(2^{10}+2^{10}\times3\right)}{3^8\left(2^{10}-2^9\right)}\)
\(\Leftrightarrow A=\frac{2^{10}+2^{10}\times3}{2^{10}-2^9}\)
\(\Leftrightarrow A=\frac{2^{10}\left(1+3\right)}{2^9\left(2-1\right)}\)
\(\Leftrightarrow A=\frac{2\left(1+3\right)}{2-1}\)
\(\Leftrightarrow A=\frac{2\times4}{1}\)
\(\Leftrightarrow A=8\)