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c) Ta có: \(C=7\left(x-8\right)^2-9\left(x+3\right)^2+50\)
\(=7\left(x^2-16x+64\right)-9\left(x^2+6x+9\right)+50\)
\(=7x^2-112x+448-9x^2-54x-81+50\)
\(=-2x^2-166x-31\)
\(=-2\cdot\dfrac{1}{49}-166\cdot\dfrac{-1}{7}-31\)
\(=\dfrac{-359}{49}\)
g) Ta có: \(G=x^{17}-3x^{16}+3x^{15}-3x^{14}+...+3x\)
\(=x^{17}-x^{16}\left(x+1\right)+x^{15}\left(x+1\right)-x^{14}\left(x+1\right)+...+x\left(x+1\right)\)
\(=x^{17}-x^{17}-x^{16}+x^{16}+x^{15}-x^{15}-x^{14}+...+x^2+x\)
=x
=2
a) 1/4 + 5/6 = 13/12
b) 1/8 + 3/4 =7/8
c) 1/4 + 1/5 = 9/20
d) 2/3 + 2/7 = 20/21
6/
a) \(\dfrac{4}{16}+\dfrac{1}{4}=\dfrac{1}{4}+\dfrac{1}{4}=\dfrac{2}{4}=\dfrac{1}{2}\)
b) \(\dfrac{15}{25}+\dfrac{6}{10}=\dfrac{3}{5}+\dfrac{3}{5}=\dfrac{6}{5}\)
c) \(\dfrac{5}{9}+\dfrac{21}{27}=\dfrac{5}{9}+\dfrac{7}{9}=\dfrac{12}{9}=\dfrac{4}{3}\)
a)36/48>12/48
=>6/8>3/12
b)135/225<180/225
=>15/25<36/45
c)1575/2835>1323/2835
=>15/27>49/105
Chúc e học tốt
Bạn ơi bạn có thể trình bày cái phần rút gọn được ko
\(\dfrac{42}{48}\)=\(\dfrac{6}{7}\) và \(\dfrac{8}{32}\)=\(\dfrac{1}{4}\)
\(\frac{2}{8}\)+\(\frac{5}{6}\)
=\(\frac{1}{4}\)+\(\frac{5}{6}\)
=\(\frac{6}{24}\)+\(\frac{20}{24}\)
=\(\frac{13}{12}\)
\(a,\dfrac{5}{4}+\dfrac{7}{3}=\dfrac{15}{12}+\dfrac{28}{12}=\dfrac{43}{12}\\ b,\dfrac{4}{5}\times\dfrac{5}{8}=\dfrac{4}{8}=\dfrac{1}{2}\\ c,\dfrac{2}{3}-\dfrac{3}{8}=\dfrac{16}{24}-\dfrac{9}{24}=\dfrac{7}{24}\\ d,\dfrac{5}{6}:\dfrac{1}{3}=\dfrac{5}{6}\times\dfrac{1}{3}=\dfrac{5}{18}\)
a) \(\dfrac{5}{4}+\dfrac{7}{3}=\dfrac{15}{12}+\dfrac{28}{12}=\dfrac{43}{12}\)
b) \(\dfrac{4}{5}\cdot\dfrac{5}{8}=\dfrac{20}{40}=\dfrac{1}{2}\)
c) \(\dfrac{2}{3}-\dfrac{3}{8}=\dfrac{16}{24}-\dfrac{9}{24}=\dfrac{7}{24}\)
d) \(\dfrac{5}{6}:\dfrac{1}{3}=\dfrac{5}{6}\cdot\dfrac{3}{1}=\dfrac{15}{6}\)
đề bài đâu