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If a^2+b^2=5 and a+b=3, then ab=

Sagot :

Answer:

  ab = 2

Step-by-step explanation:

You know that ...

  (a +b)^2 = a^2 +2ab +b^2

Rearranging, we can solve for ab ...

  2ab = (a^2 +b^2) -(a +b)^2

  ab = ((a +b)^2 -(a^2 +b^2))/2 = (3^2 -5)/2

  ab = 2