Q. Factor the following expression completely.x4−x3−90x2−x2+x+90Answer:
Identify like terms: Identify like terms in the expression x4−x3−90x2−x2+x+90 and combine them.Calculation: −90x2−x2=−91x2The expression becomes x4−x3−91x2+x+90.
Combine like terms: Look for common factors in groups of terms. We can group the first three terms and the last three terms separately.Grouping: (x4−x3−91x2)+(x+90)
Group terms: Factor out the greatest common factor from the first group, which is x2. Calculation: x2(x2−x−91) The expression now is x2(x2−x−91)+(x+90).
Factor out common factor: Notice that there is no common factor in the second group (x+90), so we leave it as is.The expression remains x2(x2−x−91)+(x+90).
Factor quadratic: Now, we need to factor the quadratic x2−x−91. Look for two numbers that multiply to −91 and add up to −1.Calculation: The numbers are −13 and 7 because −13×7=−91 and −13+7=−6.There is a mistake here; the numbers should add up to −1, not −6. We need to find the correct pair of numbers.
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