Answer:
16 y squared minus x squared
Explanation:
The other all expressions except 16y²-x² doesn't complete the square and its difference. Then we can check 16y²-x²,
Now take the expression 16y²-x² and we can try to solve it.
We can simplify the terms separately to associate them as perfect squares,
→ 16y² = (4y)² --- (1)
→ x² = (1x)² --- (2)
Now we can take the difference of eq. (1) and eq. (2),
→ 16y²-x²
→ (4y)²-(1x)² --- (3)
Now eq. (3) shows a difference of squares.
Another representation is,
→ (4y - x) (4y + x)
→ 16y²- x²
→ (4y)²- (1x)²
Therefore, the expression 16y²-x² shows a correct difference of squares.