Question

$left { {{} 5^{y-1} * 5^{x+y} =25 atop {y-x=7}} right.$
СРОЧНО!

Answer 1

5^(y-1)*5^(x+y)=25
y-x=7 ⇒y=7+x

5^(7+x-1)*5^(x+7+x)=25

5^(6+x)*5^(2x+7)=5²

5^(6+x+2x+7)=5²

5^(3x+13)=5²

3x+13=2

3x=-11

x= -11/3 =-3 2/3    y= 7+(-3 2/3)=3 1/3