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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
100 is the common denominator so
70/100 + 20/100 90/100 = 9/10
Answer:
60%
Step-by-step explanation:
45 pieces out of 75 pieces are chocolate
45/75
Divide: 45/75 = 0.6
To get percentage from a decimal, move the decimal point to the right two place values
0.6 => 60%
60% of his candy are chocolate
Answer:
Since b^2 -4ac = 256 we have 2 real distinct root roots
Step-by-step explanation:
4x^2+12x=7
We need to subtract 7 to get it in the proper form
4x^2+12x-7=7-7
4x^2+12x-7=0
The discriminant is b^2 -4ac
when the equation is ax^2 +bx+c
so a =4 b=12 and c=-7
(12)^2 - 4(4)(-7)
144 +112
256
If b^2 -4ac > 0 we have 2 real distinct roots
If b^2 -4ac = 0 we have one real root
If b^2 -4ac < 0 we have two complex root
Since b^2 -4ac = 256 we have 2 real distinct root roots