( Х - 1 )/5 = ( 5 - Х )/2 + ( 3х/4 )
<span>4( Х - 1 ) = 10( 5 - Х ) + 15х </span>
<span>4х - 4 = 50 - 10х + 15х </span>
<span>4х - 4 = 50 + 5х </span>
<span>5х - 4х = - 4 - 50 </span>
<span>Х = - 54</span>
(a^2+2ab+b^2)(a^2-2ab+b^2)=a^4-2a^3b+a^2b^2+2a^3b-4a^2b^2+2ab^3+a^2b^2-2ab^3+b^4=a^4-2a^2b^2+b^4=25-20+2=7