Solution: Let $ t = 2y + 1 \Rightarrow y = \fract - 12 $. Substitute into $ h(t) $: $ h(t) = \left(\fract - 12\right)^3 - 5\left(\fract - 12\right) + 6 $. Simplify: $ h(t) = \frac(t-1)^38 - \frac5(t-1)2 + 6 $. Now replace $ t $ with $ y^2 - 1 $: $ h(y^2 - 1) = \frac(y^2 - 2)^38 - \frac5(y^2 - 2)2 + 6 $. Expand and combine terms (if required). \boxed\frac(y^2 - 2)^38 - \frac5(y^2 - 2)2 + 6 - Nelissen Grade advocaten