Chapter 9: Problem 40
Find the quadratic function \(f(x)=a x^{2}+b x+c\) for which \(f(-1)=5, f(1)=3,\) and \(f(2)=5\)
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Chapter 9: Problem 40
Find the quadratic function \(f(x)=a x^{2}+b x+c\) for which \(f(-1)=5, f(1)=3,\) and \(f(2)=5\)
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Find the following matrices: a. \(A+B\) b. \(A-B\) c. \(-4 A\) d. \(3 A+2 B\) $$ A=\left[\begin{array}{lll} {6} & {2} & {-3} \end{array}\right], B=\left[\begin{array}{lll} {4} & {-2} & {3} \end{array}\right] $$
Find (if possible) the following matrices: a. \(A B\) b. \(B A\) $$ A=\left[\begin{array}{ll} {2} & {4} \\ {3} & {1} \\ {4} & {2} \end{array}\right], \quad B=\left[\begin{array}{rrr} {3} & {2} & {0} \\ {-1} & {-3} & {5} \end{array}\right] $$
Solve the system: $$ \left\\{\begin{array}{c} {2 \ln w+\ln x+3 \ln y-2 \ln z=-6} \\ {4 \ln w+3 \ln x+\ln y-\ln z=-2} \\ {\ln w+\ln x+\ln y+\ln z=-5} \\ {\ln w+\ln x-\ln y-\ln z=5} \end{array}\right. $$ (Hint: Let \(A=\ln w, B=\ln x, C=\ln y,\) and \(D=\ln z .\) Solve the system for \(A, B, C,\) and \(D .\) Then use the logarithmic equations to find \(w, x, y, \text { and } z .)\)
Solve each system of equations using matrices. Use Gaussian elimination with back-substitution or Gauss-Jordan elimination. $$ \left\\{\begin{aligned} w+x+y+z &=4 \\ 2 w+x-2 y-z &=0 \\ w-2 x-y-2 z &=-2 \\ 3 w+2 x+y+3 z &=4 \end{aligned}\right. $$
Let $$ A=\left[\begin{array}{rr} {-3} & {-7} \\ {2} & {-9} \\ {5} & {0} \end{array}\right] \text { and } B=\left[\begin{array}{rr} {-5} & {-1} \\ {0} & {0} \\ {3} & {-4} \end{array}\right] $$ Solve each matrix equation for X. $$ X-A=B $$
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