Question

ayúdenme con estas dos de matemáticas
a) ×+7=2×-5​.
b) 2(x+7)=9×
C) 3×-7=×+29
D) 2x+18=x+21​

Answer 1

Explicación paso a paso:

A)

$x + 7 = 2x - 5 \\ 7 + 5 = 2x - x \\ 12 = x$

B)

$2(x + 7) = 9x \\ 2x + 14 = 9x \\ 14 = 9x - 2x \\ 14 = 7x \\ \frac{14}{7} = x \\ x = 2$

C)

$3x - 7 = x + 29 \\ 3x - x = 29 + 7 \\ 2x = 36 \\ x = \frac{36}{2} \\ x = 18$

D)

$2x + 18 = x + 21 \\ 2x - x = 21 - 18 \\ x = 3$