Final answer:
To find the expression that equals 3B - 3C in standard form, substitute the given values of B and C into the expression and simplify.
Step-by-step explanation:
To find the expression that equals 3B - 3C in standard form, we substitute the given values of B and C into the expression and simplify.
Given:
B = -3x - 7x^2
C = -x^2 - 8 - x
Substituting:
3B - 3C = 3(-3x - 7x^2) - 3(-x^2 - 8 - x)
Simplifying:
3B - 3C = -9x - 21x^2 + 3x^2 + 24 + 3x
Combining like terms:
3B - 3C = -21x^2 - 6x + 24