Difference between revisions of "2008 AMC 10B Problems/Problem 9"
m |
m (Added answer "A" after "1") |
||
Line 7: | Line 7: | ||
==Solution== | ==Solution== | ||
− | Dividing both sides by <math>a</math>, we get <math>x^2 - 2x + b/a = 0</math>. By Vieta's formulas, the sum of the roots is <math>2</math>, therefore their average is <math>1</math>. | + | Dividing both sides by <math>a</math>, we get <math>x^2 - 2x + b/a = 0</math>. By Vieta's formulas, the sum of the roots is <math>2</math>, therefore their average is <math>1\Rightarrow \boxed{A}</math>. |
==See also== | ==See also== | ||
{{AMC10 box|year=2008|ab=B|num-b=8|num-a=10}} | {{AMC10 box|year=2008|ab=B|num-b=8|num-a=10}} |
Revision as of 19:08, 30 March 2009
Problem
A quadratic equation has two real solutions. What is the average of these two solutions?
Solution
Dividing both sides by , we get
. By Vieta's formulas, the sum of the roots is
, therefore their average is
.
See also
2008 AMC 10B (Problems • Answer Key • Resources) | ||
Preceded by Problem 8 |
Followed by Problem 10 | |
1 • 2 • 3 • 4 • 5 • 6 • 7 • 8 • 9 • 10 • 11 • 12 • 13 • 14 • 15 • 16 • 17 • 18 • 19 • 20 • 21 • 22 • 23 • 24 • 25 | ||
All AMC 10 Problems and Solutions |