Answer:
\(4a^2 - 20a+25\)
Step-by-step explanation:
Since, for a perfect square trinomial the value of discriminant = 0,
That is, if for a quadratic equation \(ax^2+bx+c\)
\(D=b^2-4ac=0\)
Then, \(ax^2+bx+c\) is a perfect square trinomial,
For \(49x^2 - 28x+16\),
\((-28)^2-4\times 49\times 16=-2352
eq 0\)
⇒ \(49x^2 - 28x+16\) is not a perfect square trinomial,
For \(4a^2 - 20a+25\),
\((-20)^2-4\times 4\times 25=400-400=0\)
⇒ \(4a^2 - 20a+25\) is a perfect square trinomial,
For \(25b^2 - 20b - 16\),
\((-20)^2-4\times 25\times -16=2000
eq 0\)
⇒ \(25b^2 - 20b - 16\) is not a perfect square trinomial,
For \(16x^2 - 24x - 9\),
\((-24)^2-4\times 16\times -9=1152
eq 0\)
⇒ \(16x^2 - 24x -9\) is not a perfect square trinomial,
