SOLUTION: Find the value of k for which the equation 3x2 − kx + 7 = 0 will have two real solutions.

Algebra ->  Quadratic Equations and Parabolas  -> Quadratic Equations Lessons  -> Quadratic Equation Lesson -> SOLUTION: Find the value of k for which the equation 3x2 − kx + 7 = 0 will have two real solutions.      Log On


   

Question 259772: Find the value of k for which the equation 3x2 − kx + 7 = 0 will have two real solutions.
Found 2 solutions by Fombitz, CharlesG2:
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
Look at the discriminant.
For real roots, D>0.
D=b%5E2-4ac
k%5E2-4%283%29%287%29%3E0
k%5E2%3E84
k%3Esqrt%2884%29 or k%3C-sqrt%2884%29

Answer by CharlesG2(834) About Me  (Show Source):
You can put this solution on YOUR website!
Find the value of k for which the equation 3x2 − kx + 7 = 0 will have two real solutions.
3x^2 -kx +7 = 0
a quadratic equation is ax^2+bx+c=0
solved by:
x+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+
b^2-4ac is the discriminant
the discriminant needs to be greater than 0
a=3, b=-k, c=7
(-k)^2-4*3*7
k^2-12*7
k^2-84
k^2 needs to be greater than 84
k=sqrt(84)=sqrt(4*21)=2*sqrt(21)=9.165151
k needs to be greater than 9.165151