Find the value of ∫∞0x e−xdx
1
-1
0
None of these
∫∞0x e−xdx=limb→∞∫b0e−x x dx =limb→∞(−xe−x−e−x)b0 =limb→∞ −be−b−e−b+1 =limb→∞ −(b+1)eb+limb→∞ 1 =limb→∞ −1eb+limb→∞ 1 using L'Hospital's theorem =1