Final answer:
To find an expression that equals 3B-3A, substitute the given expressions for B and A into the equation and simplify to get the final expression in standard form.
Step-by-step explanation:
To find an expression that equals 3B-3A in standard form, we need to substitute the given expressions for B and A into the equation.
Given: B = x-4+x² and A = 2+x².
Substituting the values into the equation: 3B-3A = 3(x-4+x²) - 3(2+x²).
Simplifying the expression: 3(x-4) + 3x² - 3(2+x²) = 3x-12 + 3x² - 6 - 3x² = 6x² - 3x - 18.
Therefore, the expression that equals 3B-3A in standard form is 6x² - 3x - 18.