1) What is area between numbers -1 and 3?
2) What is area between numbers 3 and 4?
3) What is area between numbers -1 and 4?
Is the result OK?
4) How we will calculate the marked area?

f = Function(3 + 2 * x - x^(2), -10, 10)
a = -1 (slider from -5 to 5, step 0.1)
b = 0.4 (slider from -5 to 5, step 0.1)
S = Integral(f, a, b)
c: abs(S)
text3: "$ f:y=" + (LaTeX[f]) + " $"
text2: "$\LARGE \int_{" + (LaTeX[a]) + "}^{" + (LaTeX[b]) + "}{ \left(  " + (LaTeX[f]) + " \right) }dx=" + (LaTeX[FractionText[S]]) + "\doteq" + (LaTeX[S]) + "$"
text1: "\LARGE Area\ S=" + (LaTeX[FractionText[c]]) + "\doteq" + (LaTeX[c]) + ""