You just need to plug those expressions inside the formula: it doesn't matter if they're expressions involving a variable instead of plain numbers: the formula becomes

If you want, you can simplify it by expanding the square and then multiply the two parenthesis:

Answer:
a = - 4, b = 5
Step-by-step explanation:
Expand the left side and compare the coefficients of like terms on the right side.
- 3(2x² + ax + b)
= - 6x² - 3ax - 3b
Comparing like terms with - 6x² + 12x - 15
x - term → - 3a = 12 ( divide both sides by - 3 )
a = - 4
constant term → - 3b = - 15 ( divide both sides by - 3 )
b = 5
Answer:
A: 1/3
Step-by-step explanation:
please mark this answer as brainlest
I agree with Roaltyjess<span />
A is the answer. Hope this helps!