Tính nhanh
A=\(\dfrac{43^2-11^2}{\left(36,5\right)^2-\left(27,5\right)^2}\)
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\(\frac{\left(43-11\right)\left(43+11\right)}{\left(36,5-27,5\right)\left(36,5+27,5\right)}=\frac{32.54}{9.64}\)
\(=3\)
dùng hằng đẳng thức thứ 3 ta có
(43-11)(43+11) và (36,5-27,5)(36,5+27,5)
Nên =1728 : 576=3
\(R=\frac{43^2-11^2}{36,5^2-27,5^2}\)
\(R=\frac{\left(43-11\right)\left(43+11\right)}{\left(36,5+27,5\right)\left(36,5-27,5\right)}\)
\(R=\frac{32.54}{64.9}\)
\(R=3\)
\(R=\frac{43^2-11^2}{\left(36,5\right)^2-\left(27,5\right)^2}\)
\(=\frac{\left(43-11\right)\left(43+11\right)}{\left(36,5-27,5\right)\left(36,5+27,5\right)}\)
\(=\frac{32.54}{9.64}\)
\(=\frac{6}{2}=3\)
Bạn viết sai đề bài rồi
\(S=\frac{97^3+83^3}{180}-97.83\)
\(=\frac{\left(97+83\right)\left(97^2-97.83+83^2\right)}{180}-97.83\)
\(=97^2-97.83+83-97.83\)
\(=\left(97-83\right)^2=14^2=196\)
Trả lời:
\(R=\frac{43^2-11^2}{36,5^2-27,5^2}\)
\(R=\frac{\left(43-11\right).\left(43+11\right)}{\left(36,5-27,5\right).\left(36,5+27,5\right)}\)
\(R=\frac{32.54}{9.64}\)
\(R=3\)
Đề bài sai bạn nhé
\(S=\frac{97^3+83^3}{180}-97.83\)
\(S=\frac{\left(97+83\right).\left(97^2-97.23+83^2\right)}{180}-97.83\)
\(S=97^2-97.83+83^2-97.83\)
\(S=97^2-2.97.83+83^2\)
\(S=\left(97-83\right)^2\)
\(S=14^2\)
\(S=196\)
11) \(\dfrac{5}{7}\left(\dfrac{1}{2}-\dfrac{1}{3}+\dfrac{4}{7}\right)+\left(\dfrac{1}{3}-\dfrac{1}{2}-\dfrac{4}{7}\right):\dfrac{7}{5}\)
= \(\dfrac{5}{7}\left(\dfrac{1}{2}-\dfrac{1}{3}+\dfrac{4}{7}\right)+\left(\dfrac{1}{3}-\dfrac{1}{2}-\dfrac{4}{7}\right)\cdot\dfrac{5}{7}\)
= \(\dfrac{5}{7}\left(\dfrac{1}{2}-\dfrac{1}{3}+\dfrac{4}{7}+\dfrac{1}{3}-\dfrac{1}{2}-\dfrac{4}{7}\right)\)
= \(\dfrac{5}{7}\cdot0\)
=0
12) \(\dfrac{43}{5}\left(\dfrac{17}{3}-\dfrac{16}{9}+2\right)-\dfrac{43}{5}\left(\dfrac{17}{3}-\dfrac{16}{9}\right)\)
= \(\dfrac{43}{5}\left(\dfrac{17}{3}-\dfrac{16}{9}+2-\dfrac{17}{3}+\dfrac{16}{9}\right)\)
= \(\dfrac{43}{5}\cdot2=\dfrac{43}{10}\)
11, 5/7( 1/2-1/3+1/4)+ (1/3-1/2-1/4):7/5
= 5/7.(1/2 - 1/3 + 1/4 )+( 1/3 - 1/2 - 1/4). 5/7
= 5/7.(1/2 - 2/3 + 1/4 + 1/3 - 1/2 - 1/4)
= 5/7 . -1/3
= -5/21
12, 43/5.(17/3 - 16/9 + 2)- 43/5. (17/3 - 16/9)
= 43/5.( 17/3 - 16/9 + 2 - 17/3 + 16/9)
= 43/5 . 2
= 86/5
\(A=\dfrac{\left(43-11\right)\left(43+11\right)}{\left(36.5-27.5\right)\left(36.5+27.5\right)}\)
\(=\dfrac{32\cdot54}{9\cdot64}=\dfrac{1}{2}\cdot6=3\)
\(A=\dfrac{43^2-11^2}{\left(36,5\right)^2-\left(27,5\right)^2}\)
\(=\dfrac{\left(43-11\right)\left(43+11\right)}{\left(36,5-27,5\right)\left(36,5+27,5\right)}\)
\(=\dfrac{32.54}{9.64}=\dfrac{6}{2}=3\)