(4m−2)| 6=√[42+(4m)2+(4m−2)2] ⇒6=√[16+16m2+16m2−16m+4] Squaring both sides, we get ⇒36=32m2−16m+20 ⇒8m2−4m−4=0 ⇒8m2−8m+4m−4=0 ⇒8m(m−1)+4(m−1)=0 ⇒(8m+4)(m−1)=0 ⇒ m = -4/8 = -1/2 OR m = 1 Hence, option (1) is correct.