Q. Factor the following expression completely.x4+9x3−10x2−9x2−81x+90Answer:
Combine like terms: First, combine like terms in the expression. x4+9x3−10x2−9x2−81x+90=x4+9x3−19x2−81x+90
Look for common factors: Next, look for common factors or patterns that might help in factoring the expression. In this case, there are no common factors, so we will try to factor by grouping.
Group terms for factoring: Group the terms to see if we can factor by grouping. (x4+9x3)−(19x2+81x)+90
Factor out common factors: Factor out the greatest common factor from each group. x3(x+9)−19x(x+9)+90
Try different grouping: Now, we notice that (x+9) is a common factor in two of the groups, but the last term, 90, does not contain this factor. We need to find a way to include (x+9) as a factor of 90 or find a different grouping strategy. Let's try a different grouping.
Regroup terms: Regroup the terms differently to see if we can factor by grouping in another way.(x4−10x2)+(9x3−81x)+90
Factor out common factors: Factor out the greatest common factor from each group. x2(x2−10)+9x(x2−9)+90
Factor quadratic: Notice that x2−9 is a difference of squares and can be factored further.x2(x2−10)+9x((x+3)(x−3))+90
Explore other methods: Now, we see that the expression does not have a common factor that we can factor out easily. We need to try a different approach or look for a different pattern. Let's try to factor the quadratic x2−10.
Explore other methods: Now, we see that the expression does not have a common factor that we can factor out easily. We need to try a different approach or look for a different pattern. Let's try to factor the quadratic x2−10.The quadratic x2−10 does not factor nicely since 10 is not a perfect square. We need to look for another pattern or use a different method, such as synthetic division or the rational root theorem, to factor the original expression. However, this is a complex polynomial, and it may not factor over the integers. We may have made a mistake in our approach.
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