Find the value of the function y = 3x² - 21 when x = 4.
To find the value of the function y = 3x² - 21 when x = 4, we simply substitute x = 4 into the equation.
y = 3(4)² - 21
= 3(16) - 21
= 48 - 21
= 27
Therefore, when x = 4, y = 27.