Răspuns :
folosim regula calculului prescurat
(a+b)(a-b)=a²-b²
1) x²-5²=x²-25
2)a²-√7²=a²-7
3)25²-b²=625-b²
4)✓30²-t²=30-t²
(a+b)(a-b)=a²-b²
1) x²-5²=x²-25
2)a²-√7²=a²-7
3)25²-b²=625-b²
4)✓30²-t²=30-t²