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Hey guys, | Hey guys, | ||
| − | I know it is kind of late to discuss hw14 but I'm gonna put this just in case some of you have trouble with prob.32 from section 6.3. As you might already noticed, finding classical adjoint of A using Theorem 6.3.9 requires a lot of work, not hard but time consuming. So I would recommend the formula adj(A)=det(A)*A^(-1). Don't worry if you can't find the right det(A) with Sarrus's rule because it does not always work. Just swap second and third row and you will get | + | I know it is kind of late to discuss hw14 but I'm gonna put this just in case some of you have trouble with prob.32 from section 6.3. As you might already noticed, finding classical adjoint of A using Theorem 6.3.9 requires a lot of work, not hard but time consuming. So I would recommend the formula adj(A)=det(A)*A^(-1). Don't worry if you can't find the right det(A) with Sarrus's rule because it does not always work. Just swap second and third row and you will get I(4). Then find A^(-1) with any kind of method you prefer and you will get the answer by multiplying them together. This actually works out pretty well and saves a lot of your time. Hope this will help. |
Thanks | Thanks | ||
Latest revision as of 18:01, 22 April 2010
HW 14
Hey guys,
I know it is kind of late to discuss hw14 but I'm gonna put this just in case some of you have trouble with prob.32 from section 6.3. As you might already noticed, finding classical adjoint of A using Theorem 6.3.9 requires a lot of work, not hard but time consuming. So I would recommend the formula adj(A)=det(A)*A^(-1). Don't worry if you can't find the right det(A) with Sarrus's rule because it does not always work. Just swap second and third row and you will get I(4). Then find A^(-1) with any kind of method you prefer and you will get the answer by multiplying them together. This actually works out pretty well and saves a lot of your time. Hope this will help.
Thanks
