....../49=2/7=16/......
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Bài 1: Tính
\(a.\frac{15}{16}-\frac{7}{16}=\frac{15-7}{16}=\frac{8}{16}=\frac{1}{2}\)
\(b.\frac{7}{4}-\frac{3}{4}=\frac{7-3}{4}=\frac{4}{4}=1\)
\(c.\frac{9}{5}-\frac{3}{5}=\frac{9-3}{5}=\frac{6}{5}\)
\(d.\frac{17}{49}-\frac{12}{49}=\frac{17-12}{49}=\frac{5}{49}\)
Bài 2:Rút gọn rồi tính
\(a.\frac{2}{3}-\frac{3}{9}=\frac{2}{3}-\frac{1}{3}=\frac{2-1}{3}=\frac{1}{3}\)
\(b.\frac{7}{5}-\frac{15}{25}=\frac{7}{5}-\frac{3}{5}=\frac{7-3}{5}=\frac{4}{5}\)
Học tốt. K cho mik nha
21*7^2 -11*7^2 +90*7^2 +49*125*16
=7^2* ( 21 -11+ 90 ) + 7^2* 2000
=7^2* 100 + 7^2* 2000
=7^2* ( 100+ 2000 )
=49*2100
=102900
\(\frac{7}{9}\)và\(\frac{6}{7}\)có \(BC:63\)
quy đồng : \(\frac{7\times7}{9\times7}=\frac{49}{63}\)và \(\frac{6\times9}{7\times9}=\frac{54}{63}\)
\(\Rightarrow\)Đáp án là : C
C. 49/63 và 42/63
C. 49/63 và 42/63
\(A=\frac{49^{24}.125^{10}.2^8-5^{30}.7^{49}.4^5}{5^{29}.16^2.7^{43}}\)
\(A=\frac{7^{48}.5^{30}.2^8-5^{30}.7^{49}.2^{10}}{5^{29}.2^8.7^{43}}\)
\(A=\frac{5^{30}.7^{48}.2^8.\left(1-7.2^2\right)}{5^{29}.2^8.7^{43}}=5.7^3.\left(1-7.2^2\right)=1715.\left(-27\right)=-46305\)
\(A=\frac{\left(7^2\right)^{24}.\left(5^3\right)^{10}.2^8-5^{30}.7^{49}.\left(2^2\right)^5}{5^{29}\left(2^4\right)^2.7^{43}}=\frac{7^{48}.5^{30}.2^8-5^{30}.7^{49}.2^{10}}{5^{29}.2^8.7^{43}}=\frac{7^{48}.5^{30}.2^8\left(1-7.2^2\right)}{5^{29}.2^8.7^{43}}\)
=\(7^5.5.\left(-27\right)=-2268945\)
\(A=\frac{49^{24}.125^{10}.2^8-5^{30}.7^{49}.4^5}{5^{29}.16^2.7^{48}}\)
\(A=\frac{\left(7^2\right)^{24}.\left(5^3\right)^{10}.2^8-5^{30}.7^{49}.\left(2^2\right)^5}{5^{29}.\left(2^4\right)^2.7^{48}}\)
\(A=\frac{7^{49}.5^{30}.2^8-5^{30}.7^{49}.2^{10}}{5^{29}.2^8.7^{48}}\)
\(A=\frac{7^{48}.5^{30}.2^8\left(1-28\right)}{5^{29}.2^8.7^{48}}\)
\(A=5.\left(-27\right)\)
\(A=-135\)
14/49=2/7=16/56
Chúc bạn học tốt
HYC-23/1/2022
\(\frac{14}{49}=\frac{2}{7}=\frac{16}{56}\)