Given,
⇒(2x+1)5+(x+1)6=3⇒(2x+1)(x+1)5(x+1)+6(2x+1)=3⇒(2x+1)(x+1)5x+5+12x+6=3⇒(2x2+2x+x+1)17x+11=3⇒(2x2+3x+1)17x+11=3⇒17x+11=3(2x2+3x+1)⇒17x+11=6x2+9x+3⇒6x2+9x−17x+3−11=0⇒6x2−8x−8=0⇒2(3x2−4x−4)=0⇒3x2−4x−4=0⇒3x2−6x+2x−4=0⇒3x(x−2)+2(x−2)=0⇒(3x+2)(x−2)=0⇒(3x+2) or (x−2)=0 [Using Zero-product rule] ⇒3x=−2 or x=2⇒x=3−2 or x=2.
Hence, x={2,3−2}.