Let's solve the quadratic expression $6y^2 - 7y + 9$ when $y = 4$.

We substitute $y = 4$ into the expression:

$6(4)^2 - 7(4) + 9$

1. First, calculate $4^2$:

$4^2 = 16$

2. Now, substitute $16$ into the equation:

$6(16) - 7(4) + 9$

3. Multiply the terms:

$6 \times 16 = 96$ $7 \times 4 = 28$

4. Substitute these into the equation:

$96 - 28 + 9$

5. Finally, perform the addition and subtraction:

$96 - 28 = 68$ $68 + 9 = 77$

Thus, the value of $6y^2 - 7y + 9$ when $y = 4$ is 77.

Would you like more details on this, or do you have any other questions?

Here are 5 related questions to consider:

1. How do you solve a quadratic equation for different values of $y$?
2. How would the solution change if the coefficient of $y^2$ was different?
3. Can we solve this expression by factoring?
4. How do quadratic expressions behave when graphed?
5. What is the significance of the discriminant in quadratic equations?

Tip: When dealing with quadratics, always check if you can factor the equation before solving it through substitution.