calculam pe a
prima paranteza= (6/10*x²+1/2*x²+2/5*x²)=x²(3/5+1/2+2/5)=x²*3/2
(2/5x)²=4x²/25
(2/5x)²:16/40=(2/5x)² *40/16=4x²/25 * 40/16=2x²/5
deci a=3x²/2-2x²/5=11x²/10
b=[16x²/25+9x²/25]:1/2+x²/5=x²* 2/1+x²/5=11x²/5
Final: a/b=11x²/10: 11x²/5=11x²/10 * 5/11x²=1/2
