Find the zeros of each function by using a graph and a table f(x)=x^2+3x-18.
1 answer:
1) Finding the zeros of this function f(x) =x² +3x -18
f(x) = x²+3x-18 <em>Factoring this equation, and rewriting it</em>
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<em>Which two numbers whose sum is equal to 3 and their product is equal to 18?</em>
<em>6 -3 = 3 and 6 *-3 = -18</em>
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<em>So we can rewrite as (x +6) (x-3)</em>
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(x+6)(x-3)=0 <em>Applying the Zero product rule, to find the roots</em>
x+6=0,
x=-6
x-3=0,
x=3
S={3,-6}
2) Setting a table, plugging in the values of x into the factored form: (x-6)(x-3)
x | y |
1 | -14 (1 +6)(1-3) =-14
2 | -8 (2 +6)(2-3) =-8
3 | 0
4 | 10
-5 | -8
-6 | 0
3) Plotting the function:
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Then, we define a variable:
x: score of Mona's last test
We write now the inequality that models the problem:
From here, we clear the value of x:
Answer:
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x = 87