Question

tìm x

a) 65 – 4^{x +2}= 201⁰                                        b) 5^2-3 -2 . 5² = 5² . 3

c) ( 19x + 2.5² ):14 = (13-8)²- 4²                   d) 2^x+1 – 2^x =32

Answer 1

\(c,\left(19x+2.5^2\right):14=\left(13-8\right)^2-4^2\\ =>\left(19x+50\right):14=5^2-4^2\\ =>\left(19x+50\right):14=9\\ =>19x+50=9\times14\\ =>19x+50=126\\ =>19x=126-50\\ =>19x=76\\ =>x=76:19\\ =>x=4\\ d,2^{x+1}-2^x=32\\ =>2^{x+1-x}=2^5\\\)

đề hơi sai sai 

Answer 2

( 19x + 2.5² ):14 = (13-8)²- 4² 

`(19x+50) :14 = 5^2-4^2`

`(19x+50) :14 =25-16=9`

`19x+509*14=126`

`19x=126-50=76`

`x=76/19=4`

Vậy `x=4`

`2^(x+1)-2^x =32`

`2^x *2-2^x=32`

`2^x(2-1)=32`

`2^x *1=32`

`2^x=2^5`

`=> x=5`