Question

2. Justify each step of the proof.

Answer 1

Hello,

2(x²+5)=60
<==>x²+5=30 (divided teh 2 members by the positive 5 :keep the equality)
<==>x²-25=0 (substract 25 from 2 members)
<==>(x-5)(x+5)=0 (remarquable product a²-b²=(a+b)(a-b))
<==> x= 5 or x=-5 (a product if null if one at least of its factor is null)