Carry out the binomial expansion in the numerator:
Then the 9⁴ terms cancel each other, so in the limit we have
Since <em>h</em> is approaching 0, that means <em>h</em> ≠ 0, so we can cancel the common factor of <em>h</em> in both numerator and denominator:
Then when <em>h</em> converges to 0, each remaining term containing <em>h</em> goes to 0, leaving you with
or choice C.
Alternatively, you can recognize the given limit as the derivative of <em>f(x)</em> at <em>x</em> = 9:
We have <em>f(x)</em> = <em>x</em> ⁴, so <em>f '(x)</em> = 4<em>x</em> ³, and evaluating this at <em>x</em> = 9 gives the same result, 2916.
Subst for f and t in...
9t+3ft+12 = 9×21 + 3×3×21 + 12 = 390
Step-by-step explanation:
Let's say the two digit number is 10x + y, where x is the first digit and y is the second digit.
The sum of the digits is 8:
x + y = 8
If 8 is subtracted from the number, the digits switch place.
10x + y − 8 = 10y + x
Simplify the second equation:
9x − 8 = 9y
Substitute from the first equation.
y = 8 − x
9x − 8 = 9 (8 − x)
9x − 8 = 72 − 9x
18x = 80
x = 4.444
There's a problem. x isn't an integer. Are you sure you copied the problem correctly? Perhaps you meant if 18 is subtracted from the number, the digits switch place.
9x − 18 = 9 (8 − x)
9x − 18 = 72 − 9x
18x = 90
x = 5
y = 8 − x
y = 3
So the number is 53.
Let's get the denominators of both fractions to be the same before moving on, aka finding the least common multiple of the denominators.
8 and 3 have a LCM of 24. So, we have to multiply 1/3 by 8 and 3/8 by 3.
1/3 * 8/8 = 8/24
3/8 * 3/3 = 9/24
There is only 1/24 of juice left in the bottle if the remaining amount of juice has 1/3 poured out.
Hope that helped.
