làm thế nào tính = 7 bằng 3 dòng?

77 tròn

77 nhé

\(\frac{49^6\times5-7^{11}}{\left(-7\right)^{10}\times5+2\times49^5}\)

\(=\frac{7^{12}\times5-7^{11}}{7^{10}\times5+2\times7^{10}}\)

\(=\frac{7^{11}.\left(5-1\right).7}{7^{10}.\left(5+2\right)}\)

\(=\frac{7^2.4}{6}\)

\(=\frac{55}{6}\)

\(7^x\times49=7^{32}\)

\(\Rightarrow7^x\times7^2=7^{32}\)

\(\Rightarrow7^{x+2}=7^{32}\)

\(\Rightarrow x=30\)

(7 mũ x , nhân cho 49 =7 mũ 32 )

Giải:

\(7^x.49=7^{32}\)

\(\Rightarrow7^x.7^2=7^{32}\)

Áp dụng công thức nhân hai lũy thừa cùng cơ số, ta có:

\(\Rightarrow7^x=7^{32}:7^2\)

\(\Rightarrow7^x=7^{32-2}\)

\(\Leftrightarrow7^x=7^{30}\)

\(\Rightarrow x=30\)

A

\(\dfrac{25}{49}\) a nhé

A

\(\left\{{}\begin{matrix}a=\dfrac{35}{49}=\dfrac{5}{7}\\b=\sqrt{\dfrac{5^2}{7^2}}=\dfrac{5}{7}\\c=\dfrac{\sqrt{5^2}+\sqrt{35^2}}{\sqrt{7^2}+\sqrt{49^2}}=\dfrac{5+35}{7+49}=\dfrac{5}{7}\\d=\dfrac{\sqrt{5^2}-\sqrt{35^2}}{\sqrt{7^2}-\sqrt{49^2}}=\dfrac{5-35}{7-49}=\dfrac{5}{7}\end{matrix}\right.\)

\(\Rightarrow a=b=c=d=\dfrac{5}{7}\)

\(a=\dfrac{35}{49};b=\dfrac{5}{7}\\ c,=\dfrac{5+35}{7+49}=\dfrac{12}{14}=\dfrac{6}{7}\\ d,=\dfrac{5-35}{7-49}\)

Áp dụng t/c dtsbn:

\(\dfrac{5}{7}=\dfrac{35}{49}=\dfrac{5+35}{7+49}=\dfrac{5-35}{7-49}\) hay \(a=b=c=d\)