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valkas [14]
3 years ago
5

What are the solutions to the equation x2 = 81?   A. 40.5 only   B. 40.5 and –40.5   C. 9 and –9   D. 9 only

Mathematics
2 answers:
Tema [17]3 years ago
5 0
x^2=81\ then\ x=9\ and\ x=-9\\\\because:(-9)^2=81\ and\ 9^2=81


x^2=81\to x=-\sqrt{81}\ and\ x=\sqrt{81}\to x=-9\ and\ x=9
Andreyy893 years ago
4 0

Answer:

C. 9 and -9

Step-by-step explanation:

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for the 45° right triangle

a = b     so      2a² = hyp²                       perimeter 45 = a + a + hyp    

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for the 30° right triangle

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a  = hyp(1/2)           b = hyp(1/2)(√3)

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        =  (1/2)hyp[ 1 + √3 + 2]                  factored out a 1/2

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which is greater  P45 or P30?   vso I set both perimeters equal to each other

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      hyp (√2 + 1)     =    (1/2)hyp[ 3 + √3]            the hyp cancel

               (√2 + 1)     =    (1/2)[ 3 + √3]                    still tough to tell  needed

               1.414 + 1    =    (1/2)[ 3 + 1.732]                to go to the calsulator

                 2.414      vs    1/2( 4.732)

                 2.414      >     2.366        thus P45 > P30    < -----  Final Answer

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