Question

1 ) tim x 

A)     (19x + 2 .5^{2) :} 14 = (13-8)² - 4²

B)       2 . 3³ = 10 . 3^{12 .}  8 . 27⁴

2) tim x thuoc N

a) 390 - ( x - 7 ) = 169 : 13

c) x - 6 : 2 - ( 48 - 24 ) : 2 : 6 - 3 = 0

d) x + 5 . 2 - ( 32 + 16 . 3 : 6 - 15 ) = 0

 

Answer 1

\(\left(19x+2.5^2\right):14=\left(13-8\right)^2-4^2\)

<=> \(\left(19x+50\right):14=25-16\)

<=> \(\left(19x+50\right):14=9\)

<=> \(19x+50=126\)

<=> \(19x=76\)

<=> \(x=4\)

câu B làm j có \(x\)để tìm

\(390-\left(x-7\right)=169:13\)

<=> \(390-x+7=13\)

<=> \(390-x=6\)

<=> \(x=384\)

\(x-6:2-\left(48:24\right):2:6-3=0\)

<=> \(x-3-2:2:6=3\)

<=> \(x-3-\frac{1}{6}=3\)

<=> \(x=\frac{37}{6}\)

\(x+5.2-\left(32+16.3:6-15\right)=0\)

<=> \(x+10-25=0\)

<=> \(x=15\)

Answer 2

2 . 3^x = 10 . 3¹² . 8 . 27⁴

Answer 3

viet sai y B