Find total area across the x-axis

01

Press these keys

2ndTRACE2:zerofnInt(

02

Walkthrough

1
Find zeros
Graph and locate every x-axis crossing inside the interval.
2
Split intervals
Integrate each sign-constant region separately.
3
Make areas positive
Add absolute values of the signed integrals.

03

Worked example

Find total area between y=x−1 and the x-axis from x=0 to 3.

NORMAL FLOAT AUTO REAL MPzero at x=1|fnInt(X−1,X,0,1)|+|fnInt(X−1,X,1,3)|2.5

AnswerTotal area = 2.5 square units.