Question

a. 5^x . 5¹⁴ = 5⁷⁸

b. 7^x . 49 = 7²⁷           

^{mn ơi giúp mik vớiiiii}

Answer 1

\(a,\text{ }5^x\cdot5^{14}=5^{78}\)

\(5^{14+x}=5^{78}\)

\(\Rightarrow\text{ }14+x=78\)

\(x=78-14\)

\(x=64\)

Answer 2

\(b,\text{ }7^x\cdot49=7^{27}\)

\(7^x\cdot7^2=7^{27}\)

\(7^{2+x}=7^{27}\)

\(\Rightarrow\text{ }2+x=27\)

\(x=27-2\)

\(x=25\)

Answer 3

a,       5^x . 5¹⁴ = 5⁷⁸ 

          5^x = 5⁷⁸ : 5¹⁴ 

         5^x = 5⁶⁴

=> x = 64 

Vậy x = 64 

b , 7^x . 49 = 7²⁷

    7^x . 7² = 7²⁷

    7^x = 7^{27 - 2} 

    7^x = 7²⁵ 

=> x = 25 

Chúc bn hc tốt <3

Answer 4

a) 5^x . 5¹⁴ = 5⁷⁸

5^x = 5⁷⁸ : 5¹⁴

5^x = 5⁶⁴

=> x = 64

Vậy x = 64

b) 7^x . 49 = 7²⁷

7^x . 7² = 7²⁷

7^x = 7²⁷ : 7²

7^x = 7²⁵

=> x = 25

Vậy x = 25

=))

Answer 5

\(a,5^x\times5^{14}=5^{78}\)

\(\Rightarrow5^x=5^{78}\div5^{14}\)

\(\Rightarrow5^x=5^{64}\)

\(\Rightarrow x=64\)

Answer 6

a. 5^x . 5¹⁴ = 5⁷⁸

\(\Leftrightarrow\) 5 ^{x + 14} = 5⁷⁸

\(\Leftrightarrow\) x + 14 = 78

\(\Leftrightarrow\) x = 64

Vậy x = 64

b. 7^x . 49 = 7²⁷

\(\Leftrightarrow\) 7^x . 7² = 7²⁷

\(\Leftrightarrow\) 7 ^{x + 2} = 7²⁷

\(\Leftrightarrow\) x + 2 = 27

\(\Leftrightarrow\) x = 25

Vậy x = 25

Answer 7

cám ơn mn nhìu nhé

Answer 8

\(7^x\times49=7^{27}\)

\(\Rightarrow7^x\times7^2=7^{27}\)

\(\Rightarrow7^x=7^{27}\div7^2\)

\(\Rightarrow7^x=7^{25}\)

\(\Rightarrow x=25\)