The error in Sarah's explanation is that she incorrectly identified that b=-4. In reality, b=-4. The correct statement should be:
"I know that a=5, b=-4, and c=-9. Now I need to find factors of 5*(-9) that add to -4."
Sarah was explaining her first step in factoring, but made an error in her explanation. Factor: 5x^2-4x-9 Sarah said, “I know that a=5, b=-4, and c=-9. Now I need to find factors of -8 that add to -4
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