Question

find the value of b for which the roots of the equation 9x^2 -bx +81 will be equal​

Answer 1

Step-by-step explanation:

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Answer 2

Answer:

For equal roots, the discriminant of the quadratic equation is equal to zero.

On comparing with Ax²+Bx+C=0, we get A=9, B= -b, and C=81.

D= Discriminant = B²-4AC

D = 0 for equal roots

So, b²-4(9)(81) = 0

Or b²= 4 * 9 * 81

or b² = 2² * 3² * 9²

Therefore, b = ± 2*3*9 = ±54