Tính nhanh giá trị của mỗi phân số sau:
a,15 x (\(\frac{212121}{434343}\)+ \(\frac{333333}{353535}\))
b,\(\frac{\text{639 x 721721}}{721x639639}\)
c,\(\frac{327x412+400}{328x412-12}\)
d,9x(\(\frac{151515}{171717}\)+ \(\frac{131313}{181818}\))
ai đúng mình tick
a) \(15\times\left(\frac{212121}{434343}+\frac{333333}{353535}\right)=15\times\left(\frac{21\times10101}{43\times10101}+\frac{33\times10101}{35\times10101}\right)\)
\(=15\times\left(\frac{21}{43}+\frac{33}{35}\right)=\frac{6462}{301}\)
b) \(\frac{639\times721721}{721\times639639}=\frac{639\times721\times1001}{721\times639\times1001}=1\)
c) \(\frac{327\times412+400}{328\times412-12}=\frac{\left(328-1\right)\times412+400}{328\times412-12}=\frac{328\times412-412+400}{328\times412-12}\)
\(=\frac{328\times412-12}{328\times412-12}=1\)
d) \(9\times\left(\frac{151515}{171717}+\frac{131313}{181818}\right)=9\times\left(\frac{15\times10101}{17\times10101}+\frac{13\times10101}{18\times10101}\right)=9\times\left(\frac{15}{17}+\frac{13}{18}\right)\)
\(=9\times\frac{491}{306}=\frac{491}{34}\)
thank bn