Final answer:
An expression for 2c - d given that c = y + 5 and d = y^2 - y - 9 is found by substituting c and d and simplifying the result. The simplified expression in standard form is -y^2 + 3y + 19.
Step-by-step explanation:
To find an expression for 2c - d given that c = y + 5 and d = y^2 - y - 9, we first need to substitute the expressions for c and d into the equation 2c - d.
Substitute c into the equation 2c - d:
Now, substitute d:
Combine the expressions:
- 2c - d = (2y + 10) - (y^2 - y - 9)
- = 2y + 10 - y^2 + y + 9
Combine like terms:
The expression 2c - d in standard form is -y^2 + 3y + 19.