Which expression has a value that is a rational number?
1 answer:
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<h3>To find the product of 42.12 and 10^3, move the decimal point in 42.12 3 places to the right because 10^3 has 3 zeros</h3>
<em><u>Solution:</u></em>
Given that,
Which means,
Here, the exponent of 10 is positive ( which is 3)
When the exponent is positive, we have to move the decimal point to right
When you multiply a number by a power of 10, ( 10!, 10^2, and so on ) move the decimal point of the number to the right the same number of places as the number of zeros in the power of 10
Here, exponent is 3 , therefore move the decimal point right 3 places in 42.12
Therefore,
Answer:
C
Step-by-step explanation:
Calculate AC using Pythagoras' identity in ΔABC
AC² = 20² - 12² = 400 - 144 = 256, hence
AC = = 16
Now find AD² from ΔACD and ΔABD
ΔACD → AD² = 16² - (20 - x)² = 256 - 400 + 40x - x²
ΔABD → AD² = 12² - x² = 144 - x²
Equate both equations for AD², hence
256 - 400 + 40x - x² = 144 - x²
-144 + 40x - x² = 144 - x² ( add x² to both sides )
- 144 + 40x = 144 ( add 144 to both sides )
40x = 288 ( divide both sides by 40 )
x = 7.2 → C