I think its D. $1,800 because 10.4 multiplied by twelve is 124.8 and if you multiply that by 15 you get $1.872.
For this case we have to:
x: Represents the unknown number
y: Represents the exponent of base 10
So, considering a system of equations we have:
From the first equation we have:
Substituting in the second equation:
We choose the positive value:
So, the number is 0.4.
So:
Thus, the exponent is 5.
Answer:
Yara use 0.4 and
If the perimeter is 98 cm, the sum of the lengths of two adjacent sides is 49 cm.
... (2x -1) + (3x +5) = 49 . . . . use the given information and relation
... 5x +4 = 49 . . . . . . . . . . . simplify
... 5x = 45 . . . . . . . . . . . . . . . subtract 4
... x = 9 . . . . . . . . . . . . . . . . . divide by 5
The left side dimension is then
... 2x -1 = 2·9 -1 = 17 . . . . cm
The top dimension is
... 3x +5 = 3·9 +5 = 32 . . . . cm
The rectangle is 17 cm by 32 cm.
We know that x > 2 ( or : x ≠ +/- 2 )
We have to factorize the numerator and the denominator:
x² - x - 6 = x² - 3 x + 2 x - 6 = x ( x - 3 ) + 2 ( x - 3 ) = ( x - 3 ) ( x + 2 )
x ² - 4 = ( x - 2 ) ( x + 2 )
I think the answer is B, if not not mistaken.