Question

Verificați ca 14 (1 supra radical din 2 +1 ......

Answer 1

14[1/(√2+1)+1/(√2+3)-47/7(6√2+5)]=
=14[(√2-1)/(√2+1)(√2-1)+(√2-3)/(√2+3)(√2-3)-47(6√2-5)/7(6√2+5)(6√2-5)]=
=14[(√2-1)/(2-1)+(√2-3)/(2-9)-47(6√2-5)/7(72-25)]=
=14[(√2-1)/(2-1)+(√2-3)/(2-9)-47(6√2-5)/7(72-25)]=
=14[(√2-1)/1+(√2-3)/(-7)-47(6√2-5)/7×47]=
=14[(7√2-7-√2+3-6√2+5)/7]=
=14[(-7+3+5)/7]=
=14(1/7)=2