1
0
729
9
81

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This was the easiest problem I could post and still only 60 % people could solve it . !!!! Amazing !!!!!!

A Former Brilliant Member
- 6 years, 1 month ago

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What do you think was the most incorrect answer that the 40% got wrong?

Lew Sterling Jr
- 6 years, 1 month ago

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Maybe ...................
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9
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A Former Brilliant Member
- 6 years, 1 month ago

5 Helpful
0 Interesting
0 Brilliant
0 Confused

(9x)=81^2. or.x=(81/3)^2. or,x=27^2=729

2 Helpful
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9 * x=81 * 81

x=6561/9

x=81

1 Helpful
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This would mean that you need to calculate $81^2$ then divide by $9$ . Which is more work than needed.

0 Helpful
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sqrt(9*x)=81

3*sqrt(x)=81

sqrt(x)=27

x=729

0 Helpful
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Since (9x)^1/2=81, then 9x=81^2=9^4. So x=(9^4)/9=9^3=729.

0 Helpful
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√9×x=81 Squaring both side 9×x=81×81 X=729

0 Helpful
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More common sense than math. I knew 3 x 27 = 81. So I just squared 27 to get 729.

0 Helpful
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Nice shortcut :)

whatever operation we do , we do on both the sides , so , we square on both the sides....

0 Helpful
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(9
*
x)^.5=81
squaring both side
9
*
x=81* 81
x=81* 81/9
x=81* 9
x=729

0 Helpful
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$\sqrt{9 \times x} = 81$ $9 \times x = 81^2$ $x=\frac{81 \times 81}{9}$ $x = \boxed{729}$