Answer: -133
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Work Shown:
p-q = -7
(p-q)^2 = (-7)^2
p^2-2pq+q^2 = 49
p^2-2(-10)+q^2 = 49
p^2+20+q^2 = 49
p^2+q^2 = 49-20
p^2+q^2 = 29
By the difference of cubes formula, we can say,
p^3 - q^3 = (p-q)*(p^2+pq+q^2)
p^3 - q^3 = (p-q)*(p^2+q^2+pq)
p^3 - q^3 = (-7)*(29-10)
p^3 - q^3 = -133
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Here's another way to solve:
p-q = -7
p = q-7
pq = -10
(q-7)*q = -10
q^2-7q = -10
q^2-7q+10 = 0
(q-5)(q-2) = 0
q-5 = 0 or q-2 = 0
q = 5 or q = 2
If q = 5, then p = q-7 = 5-7 = -2
If q = 2, then p = q-7 = 2-7 = -5
We can see that no matter what we pick for q, we'll get p*q = -10
Also, you should find that p^3-q^3 is equal to -133 for either case as well.