Question Number 10143 by konen last updated on 26/Jan/17

x∈Z  (x+4)^(x^2 −16) =1   ⇒Σx=?

Answered by mrW1 last updated on 27/Jan/17

x+4=1      ...(i)  or  x^2 −16=0  and  x+4≠0     ...(ii)    from (i):  x=−3    from (ii):  x=4    Σx=−3+4=1

Answered by sandy_suhendra last updated on 27/Jan/17

(1) x^2 −16=0         (x+4)(x−4)=0         x=4 or x=−4 (not feasible)  (2) x+4=1          x=−3  (3) x+4=−1 if x^2 −16=even number         x=−5 ⇒ (−5)^2 −16=9 (not feasible)  so Σx=4−3=1