What is the range of the function g(x) = (6x + 7)(2x - 3)?
This forms a parabola that opens upward, therefore the
range is from the vertex's y-coordinate to positive infinity.
y = (6x + 7)(2x – 3) = 12x2 – 4x – 21
y' = 24x – 4
set y' = 0 —>> x = 1/6 & sub back into original
y = [(12) • (1/6)2] – (4)(1/6) – 21
y = 1/3 – 2/3 – 21 = – 21.3333
The range is from – 21.3333 to positive infinity
.