( 3x - 5 )( 3x + 5 ) - 9x^2 = 10x
9x^2 - 25 - 9x^2 = 10x
10x = - 25
x = - 2,5
Х=2; у=4 _____________________
5^3x + 3•5^( 3x - 2 ) = 140
5^3x•( 1 + 3•( 1/25 )) = 140
5^3x = 140 : ( 28/25 )
5^3x = 125
5^3x = 5^3
3x = 3
X = 1
A^2-b^2+4a+4=(a+2)^2-b^2=(a+2-b)×(a+2+b)