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The function f(x)=2x^2
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26 Apr 2021, 12:52
26 Apr 2021, 12:52
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Question Stats:
78% (01:54) correct
21% (01:45) wrong based on 14 sessions
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The function \(f(x)=2x^2-5x\) and \(g(x)=x^2+x-3\)
What is the value of \((f*g)(-2)-[f(3)+g(2)]\)
A. -6
B. -1
C. 0
D. 1
E. 14
What is the value of \((f*g)(-2)-[f(3)+g(2)]\)
A. -6
B. -1
C. 0
D. 1
E. 14
Re: The function f(x)=2x^2
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27 Apr 2021, 06:36
27 Apr 2021, 06:36
A good one Carcass 
I guess for the 2nd half, everybody can find the value as -6. (Just put 3 in \(2x^2 - 5x\) and 2 in \(x^2+x−3 \).
For the first part: put the value of g(x) in f(x). This will create a following equation.
2\((x^2+x-3)^2\) -5\((x^2+x-3)\)
Solving it will give a value of 7.
At last, 7-6 = 1
Hence, D
I guess for the 2nd half, everybody can find the value as -6. (Just put 3 in \(2x^2 - 5x\) and 2 in \(x^2+x−3 \).
For the first part: put the value of g(x) in f(x). This will create a following equation.
2\((x^2+x-3)^2\) -5\((x^2+x-3)\)
Solving it will give a value of 7.
At last, 7-6 = 1
Hence, D
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Re: The function f(x)=2x^2
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27 Apr 2021, 10:12
27 Apr 2021, 10:12
1
Carcass wrote:
The function \(f(x)=2x^2-5x\) and \(g(x)=x^2+x-3\)
What is the value of \((f*g)(-2)-[f(3)+g(2)]\)
A. -6
B. -1
C. 0
D. 1
E. 14
What is the value of \((f*g)(-2)-[f(3)+g(2)]\)
A. -6
B. -1
C. 0
D. 1
E. 14
To find \((f*g)(-2)\) or \(f [g(-2)]\)
First plug \(x= - 2\) in \(g(x)\);
\(g(-2) = (-2)^2 + (-2) - 3 = 4 - 2 - 3 = -1\)
Now, \(-1\) serve as the input for \(f(x)\)
\(f(-1) = 2(-1)^2 - 5(-1) = 2 + 5 = 7\)
So, \((f*g)(-2) = 7\)
Plug \(x = 3\) in \(f(x)\) to find \(f(3) = 2(3)^2 - 5(3) = 18 - 15 = 3\)
Plug \(x = 2\) in \(g(x)\) to find \(g(2) = (2)^2 + 2 - 3 = 3\)
Lastly, \((f*g)(-2)-[f(3)+g(2)] = 7 - [3 + 3] = 1\)
Hence, option D
