fattty wrote:
If f(x) = 3x^2 - tx + 5 is tangents to x-axis, what is the value of a positive number t?
A. 2√15
B. 4√15
C. 3√13
D. 4√13
E. 6√15
f(x) = \(3x^2 - tx + 5\), is a quadratic equation.
Given , X-axis is a tangent to this Quadratic equation , implies there is only one root for this equation .
As a result,the Discriminant (D) for this quadratic equation
must be equal to 0.We know that \(D=b^2-4*a*c\)
Ergo, since D=0
\(t^2-4*3*5=0\)
\(t^2=60\)
\(t=2\sqrt{15}\)
KUDOS if you liked the solution.
Kanishk
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