Find all values of b that will make the polynomial a perfect square trinomial: 25z^2 + bz + 9

Question

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Answer 1

If 25z² + bz + 9 is a perfect square trinomial, then the equation 25z² + bz + 9 = 0 has a double root.  So, the discriminant must be 0.  

 

Therefore, b² - 4(25)(9) = 0

 

                              b² = 900

 

                              b = ±√900 = ±30

 

Answer 2

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