Morgan, Dakota and Taylor showed their work solving the equation 7x+5x+1=73. Identify the student with the invalid first step an
2 answers:
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Step-by-step explanation:
We have
First, 125 is a perfect cube because
and
x^3 is a perfect cube because
so we can use the difference of cubes identity
Let say we have two perfect cubes:
64 because 8×8×8=64
and 27 because 3×3×3=27 and let subtract
we know that
but using the difference of cubes identity we should get the same thing.
Remeber cube root of 64 is 4 and cube root of 27 is 3 so we have
So the difference of cubes works for real numbers. This is a good way to help remeber the identity using real numbers.
Back on to the topic,
we know that 5 is cube root of 125 and x is the cube root of x^3 so we have
Answer:
Step-by-step explanation:
If , then
. It follows that
Technically we are done, but some more simplification can be made. We can get a common denominator between 1/(x+h) and 1/x.
Now we can cancel the h in the numerator and denominator under the assumption that h is not 0.