Question

Answer 1

\(7^x.49=7^{90}\)

\(7^x.7^2=7^{90}\)

\(7^{x+2}=7^{90}\)

\(x+2=90\)

\(x=98\)

Answer 2

`7^x . 49 = 7^90 => 7^x . 7^2 = 7^90 => 7^x = 7^90 : 7^2 => 7^x = 7^88 => x=88`

Answer 3

\(7^x.49=7^{90}.\)

\(7^x.7^2=7^{90}.\)

\(7^x=7^{90}:7^2.\)

\(7^x=7^{88}.\)

Vậy \(\Rightarrow x=88.\)

Answer 4

\(7^x\cdot49=7^{90}\)

\(7^x\cdot7^2=7^{90}\)

\(7^{\left(x+2\right)}=7^{90}\)

`=>x+2=90`

`=>x=88`