Please Help The scientists believe the forest will be seriously damaged when 21 or more of the forests 200 oak trees are infecte
d by oat wilt.According to their model how many years will it take for 21 of the trees to become infected? Type the correct answer in the box use numerals instead of words. Round your answer to the nearest tenth.
1 answer:
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<h3>Answer: Choice B is correct</h3>
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Explanation:
Use a graphing tool like GeoGebra, Desmos, or your graphing calculator to plot each expression given as a separate y equation. Four parabolas should result.
The x intercept is the same as the root or zero of a function.
You should find that only choice B has a root thats larger than 4. That specific root being x = 7.
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A non-graphing approach:
You can use the quadratic formula or the factoring method to find the roots.
For choice A, it factors to (x+5)(x+6) = 0. The roots are x = -5 and x = -6 which aren't greater than 4. So we cross choice A off the list. Choices C and D are similar stories.
On the other hand, choice B factors to (x-7)(x+2) = 0 and it has roots of x = 7 and x = -2. This is another way to see why choice B is the answer.
Here are the steps for the quadratic formula for choice B
The quadratic formula is handy in case factoring is either not possible, or guess-and-check is too lengthy of a process. As you can probably tell, we could use the quadratic formula's results to help construct the factored form.