Differentiate. \[ y=\left(9 x^{2}+8\right)(5 x+4) \] \( y^{\prime}=\square \)

We are given \[ y = \left(9x^2+8\right)(5x+4). \] To differentiate, we use the product rule which states that \[ y' = u'v + uv', \] where \[ u = 9x^2+8 \quad \text{and} \quad v = 5x+4. \] 1. Differentiate \( u \): \[ u' = \frac{d}{dx}(9x^2+8)=18x. \] 2. Differentiate \( v \): \[ v' = \frac{d}{dx}(5x+4)=5. \] 3. Apply the product rule: \[ y' = (18x)(5x+4) + (9x^2+8)(5). \] 4. Expand and simplify: \[ (18x)(5x+4) = 90x^2 + 72x, \] and \[ (9x^2+8)(5) = 45x^2 + 40. \] Therefore, \[ y' = 90x^2 + 72x + 45x^2 + 40 = 135x^2 + 72x + 40. \] Thus, the derivative is \[ y' = 135x^2 + 72x + 40. \]