Quadratic Equations

Question

One of the roots of the equation 10x2−33x+c=0 is 5.3. Find the other root and the coefficient c.

One of the roots of the equation 10x²−33x+c=0 is 5.3. Find the other root and the coefficient c.

Answer 1

First, plug in the known root for x to find the value of c.

 

10(5.3)² - 33(5.3) + c = 0

10(28.09) - 174.9 + c = 0

 

c = 174.9 - 280.9

c = -106

 

Then your equation is

 

10x² - 33x - 106 = 0

 

 

Then, use the quadratic formula to find the other root.  One of them will be x=5.3.  Look for the other root.