Difference between revisions of "2002 AMC 12A Problems/Problem 1"

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{{duplicate|[[2002 AMC 12A Problems|2002 AMC 12A #1]] and [[2002 AMC 10A Problems|2002 AMC 10A #10]]}}
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== Problem ==
 
== Problem ==
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Compute the sum of all the roots of
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<math>(2x+3)(x-4)+(2x+3)(x-6)=0 </math>
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<math> \textbf{(A) } \frac{7}{2}\qquad \textbf{(B) } 4\qquad \textbf{(C) } 5\qquad \textbf{(D) } 7\qquad \textbf{(E) } 13 </math>
  
== Solution ==
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==Solution 1==
{{solution}}
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We expand to get <math>2x^2-8x+3x-12+2x^2-12x+3x-18=0</math> which is <math>4x^2-14x-30=0</math> after combining like terms. Using the quadratic part of [[Vieta's Formulas]], we find the sum of the roots is <math>\frac{14}4 = \boxed{\textbf{(A) }7/2}</math>.
  
 
== See also ==
 
== See also ==
 
{{AMC12 box|year=2002|ab=A|before=First Question|num-a=2}}
 
{{AMC12 box|year=2002|ab=A|before=First Question|num-a=2}}
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{{AMC10 box|year=2002|ab=A|num-b=9|num-a=11}}
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{{MAA Notice}}

Latest revision as of 15:44, 25 July 2024

The following problem is from both the 2002 AMC 12A #1 and 2002 AMC 10A #10, so both problems redirect to this page.

Problem

Compute the sum of all the roots of $(2x+3)(x-4)+(2x+3)(x-6)=0$

$\textbf{(A) } \frac{7}{2}\qquad \textbf{(B) } 4\qquad \textbf{(C) } 5\qquad \textbf{(D) } 7\qquad \textbf{(E) } 13$

Solution 1

We expand to get $2x^2-8x+3x-12+2x^2-12x+3x-18=0$ which is $4x^2-14x-30=0$ after combining like terms. Using the quadratic part of Vieta's Formulas, we find the sum of the roots is $\frac{14}4 = \boxed{\textbf{(A) }7/2}$.

See also

2002 AMC 12A (ProblemsAnswer KeyResources)
Preceded by
First Question
Followed by
Problem 2
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 12 Problems and Solutions
2002 AMC 10A (ProblemsAnswer KeyResources)
Preceded by
Problem 9
Followed by
Problem 11
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

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