# 2009-19 Two matrices

Let A and B be n×n matrices over the real field R. Prove that if A+B is invertible, then A(A+B)-1B=B(A+B)-1A.

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# Good luck with your midterm exam (no problems this and next week)

Good luck with the midterm exam! The next POW problem will be announced on Oct. 30.

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# Solution: 2009-18 Differential Equation

Suppose y(x)≥0 for all real x. Find all solutions of the differential equation $$\frac{dy}{dx}=\sqrt{y}$$, y(0)=0.

The best solution was submitted by Seong-Gu Jeong (정성구), 수리과학과 2007학번. Congratulations!

Here is his Solution of Problem 2009-18.

There were 2 incorrect submissions.

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# 2009-18 Differential Equation

Suppose y(x)≥0 for all real x. Find all solutions of the differential equation $$\frac{dy}{dx}=\sqrt{y}$$, y(0)=0.

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