Math!!!

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Across
  1. 4. 1,2,3,4,5
  2. 5. +,Sum
  3. 7. Famous for his Triangle
  4. 8. English mathematician physicist
Down
  1. 1. a^2 + b^2 = c^2.
  2. 2. A polynomial with three terms
  3. 3. Multiplication
  4. 6. Y=mx+b