What are some facts about expressions
1 answer:
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Answer:
35.9 grams
Step-by-step explanation:
We use the formula:
Where
q is heat released
m is mass
C_p is the constant 2.44
ΔT is change in temperature
We put the info in the formula and solve for m (mass):
The mass of ethanol is 35.9 grams
<h3>Answer:</h3>
<em>Try the answers</em>
You can try the answers to see what works. You can expect all of the choices to match the first two terms, so try some farther down. Let's see if we can get -25 from -7.
a) 3*(-7) -4 = -21 -4 = -25 . . . . this one works
b) -7 -2 = -9 . . . . ≠ -25
c) -3(-7) +2 = 21 +2 = 23 . . . . ≠ -25
d) -2(-7) +1 = 14 +1 = 15 . . . . ≠ -25
The formula that works is the first one.
_____
<em>Derive it</em>
All these formulas depend on the previous term only, so we can write equations that show the required relationships. Let the unknown coefficients in our recursion formula be p and q, as in ...
Then, to get the second term from the first, we have
... 1·p +q = -1
And to get the third term from the second, we have
... -1·p +q = -7
Subtracting the second equation from the first gives ...
... 2p = 6
... p = 3 . . . . . . . this is sufficient to identify the first answer as correct
We can find q from the first equation.
... q = -1 -p = -1 -3 = -4
So, our recursion relation is ...
Answer:
Step-by-step explanation:
So we have the expression:
And we want to evaluate it for x=-2.
So, substitute -2 for x:
Multiply:
Subtract:
The absolute value of a negative is positive. So:
And we're done!