Difference between revisions of "1961 AHSME Problems/Problem 13"

(Solution to Problem 13)
 
m (Solution)
 
Line 14: Line 14:
 
<cmath>\sqrt{t^2 \cdot (t^2 + 1)}</cmath>
 
<cmath>\sqrt{t^2 \cdot (t^2 + 1)}</cmath>
 
<cmath>\sqrt{t^2} \cdot \sqrt{t^2 + 1}</cmath>
 
<cmath>\sqrt{t^2} \cdot \sqrt{t^2 + 1}</cmath>
Remember that <math>\sqrt{t^2} = |t|</math> because square rooting a real number will always result in a [[nonnegative number]].
+
Remember that <math>\sqrt{t^2} = |t|</math> because square rooting a nonnegative real number will always result in a [[nonnegative number]].
 
<cmath>|t|\sqrt{t^2 + 1}</cmath>
 
<cmath>|t|\sqrt{t^2 + 1}</cmath>
 
The answer is <math>\boxed{\textbf{(E)}}</math>.
 
The answer is <math>\boxed{\textbf{(E)}}</math>.

Latest revision as of 08:53, 31 May 2018

Problem

The symbol $|a|$ means $a$ is a positive number or zero, and $-a$ if $a$ is a negative number. For all real values of $t$ the expression $\sqrt{t^4+t^2}$ is equal to?

$\textbf{(A)}\ t^3\qquad \textbf{(B)}\ t^2+t\qquad \textbf{(C)}\ |t^2+t|\qquad \textbf{(D)}\ t\sqrt{t^2+1}\qquad \textbf{(E)}\ |t|\sqrt{1+t^2}$

Solution

Factor out the $t^2$ inside the square root. \[\sqrt{t^2 \cdot (t^2 + 1)}\] \[\sqrt{t^2} \cdot \sqrt{t^2 + 1}\] Remember that $\sqrt{t^2} = |t|$ because square rooting a nonnegative real number will always result in a nonnegative number. \[|t|\sqrt{t^2 + 1}\] The answer is $\boxed{\textbf{(E)}}$.

See Also

1961 AHSC (ProblemsAnswer KeyResources)
Preceded by
Problem 12
Followed by
Problem 14
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 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40
All AHSME Problems and Solutions

The problems on this page are copyrighted by the Mathematical Association of America's American Mathematics Competitions. AMC logo.png