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Sum
Evaluate the following.
`int 1/("a"^2 - "b"^2 "x"^2)` dx
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Solution
Let I = `int 1/("a"^2 - "b"^2 "x"^2)` dx
`= 1/"b"^2 int 1/("a"^2/"b"^2 - "x"^2)`dx
`= 1/"b"^2 int 1/(("a"/"b")^2 - "x"^2)` dx
`= 1/"b"^2 xx 1/(2("a"/"b")) log |("a"/"b" + "x")/("a"/"b" - "x")|` + c
∴ I = `1/"2ab" log |("a" + "bx")/("a" - "bx")|` + c
Alternate Method:
Let I = `int "dx"/("a"^2 - "b"^2"x"^2) = int"dx"/("a"^2 - ("bx")^2)`
`= 1/(2 xx "a") xx 1/"b" log |("a" + "bx")/("a" - "bx")|` + c
∴ I = `1/"2ab" log |("a" + "bx")/("a" - "bx")|` + c
Notes
The answer in the textbook is incorrect.
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