To avoid rewriting the integrand as a piecewise function, you could sketch the graph and geometrically compute the area between x = 0 and x = 5.
Check your work by differentiating your answer. Make sure the coefficients are correct.
In this course, you will discover strategies to differentiate (and integrate) exponential functions. But you have not discovered this process yet. Use your calculator.
Consider what the graph of π² looks like. Is it's area function linear or quadratic?