Răspuns :
1)
x²+2x=t
t(t+2)+1=t²+2t+1=(t+1)²=(x²+2x+1)²=((x+1)²)²=k²⇒k=(x+1)² sau k=-(x+1)²
2) ((x+3)+(x+4))²=(2x+7)²=k²⇒k=2x+7 sau k=-2x-7
x²+2x=t
t(t+2)+1=t²+2t+1=(t+1)²=(x²+2x+1)²=((x+1)²)²=k²⇒k=(x+1)² sau k=-(x+1)²
2) ((x+3)+(x+4))²=(2x+7)²=k²⇒k=2x+7 sau k=-2x-7