course Mth 163 I think I may be making some simple mistakes. It has been a little while since I have used any algebra. But it is coming back to me. end program€??b?è???N{???z|}?assignment #004
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21:19:24 `q001. Note that this assignment has 4 questions If f(x) = x^2 + 4, then find the values of the following: f(3), f(7) and f(-5). Plot the corresponding points on a graph of y = f(x) vs. x. Give a good description of your graph.
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RESPONSE --> f(x) = f(3) = 3^2 + 4 f(3) = 9 + 4 = 13 / 3 = 4.333 = f So it is my understanding that ( y = 4.333 ) and ( x = 3 ) Giving the points ( 3 , 4.333 ) f(x) = f(7) = 7^2 + 4 f(7) = 49 + 7 = 56 / 7 = 8 = f ( 7 , 8 ) f(x) = f(-5) = -5^2 + 4 = -21 / -5 = 4.2 = f (-5 , 4.2 ) confidence assessment: 3
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21:24:34 f(x) = x^2 + 4. To find f(3) we replace x by 3 to obtain f(3) = 3^2 + 4 = 9 + 4 = 13. Similarly we have f(7) = 7^2 + 4 = 49 + 4 = 53 and f(-5) = (-5)^2 + 9 = 25 + 4 = 29. Graphing f(x) vs. x we will plot the points (3, 13), (7, 53), (-5, 29). The graph of f(x) vs. x will be a parabola passing through these points, since f(x) is seen to be a quadratic function, with a = 1, b = 0 and c = 4. The x coordinate of the vertex is seen to be -b/(2 a) = -0/(2*1) = 0. The y coordinate of the vertex will therefore be f(0) = 0 ^ 2 + 4 = 0 + 4 = 4. Moving along the graph one unit to the right or left of the vertex (0,4) we arrive at the points (1,5) and (-1,5) on the way to the three points we just graphed.
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RESPONSE --> I thought to solve for y that we would divide the product by x self critique assessment: 2
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21:59:56 `q002. If f(x) = x^2 + 4, then give the symbolic expression for each of the following: f(a), f(x+2), f(x+h), f(x+h)-f(x) and [ f(x+h) - f(x) ] / h. Expand and/or simplify these expressions as appropriate.
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RESPONSE --> f(a) = a^2 + 4 = ( a^2 +4 , f) f(x+2) = x^2 + 2 f(x+h) = x^2 + h f(x+h)-f(x) = (x^2 + h) - f(x) [ f(x+h) - f(x) ] / h = [(x^2 + h) -f(x)] / h confidence assessment: 1
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22:05:18 If f(x) = x^2 + 4, then the expression f(a) is obtained by replacing x with a: f(a) = a^2 + 4. Similarly to find f(x+2) we replace x with x + 2: f(x+2) = (x + 2)^2 + 4, which we might expand to get (x^2 + 4 x + 4) + 4 or x^2 + 4 x + 8. To find f(x+h) we replace x with x + h to obtain f(x+h) = (x + h)^2 + 4 = x^2 + 2 h x + h^2 + 4. To find f(x+h) - f(x) we use the expressions we found for f(x) and f(x+h): f(x+h) - f(x) = [ x^2 + 2 h x + h^2 + 4 ] - [ x^2 + 4 ] = x^2 + 2 h x + 4 + h^2 - x^2 - 4 = 2 h x + h^2. To find [ f(x+h) - f(x) ] / h we can use the expressions we just obtained to see that [ f(x+h) - f(x) ] / h = [ x^2 + 2 h x + h^2 + 4 - ( x^2 + 4) ] / h = (2 h x + h^2) / h = 2 x + h.
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RESPONSE --> I think I need to research more notes self critique assessment: 1
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22:31:44 `q003. If f(x) = 5x + 7, then give the symbolic expression for each of the following: f(x1), f(x2), [ f(x2) - f(x1) ] / ( x2 - x1 ). Note that x1 and x2 stand for subscripted variables (x with subscript 1 and x with subscript 2), not for x * 1 and x * 2. x1 and x2 are simply names for two different values of x. If you aren't clear on what this means please ask the instructor.
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RESPONSE --> f(x1) = (5x +x1) + (7+x1) f(x2) = (5x^2 +2) + (7+x2) [ f(x2) - f(x1) ] / ( x2 - x1 ) = 0 Does the x2 - x1 cancel out? confidence assessment: 2
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22:35:18 Replacing x by the specified quantities we obtain the following: f(x1) = 5 * x1 + 7, f(x2) = 5 * x2 + 7, [ f(x2) - f(x1) ] / ( x2 - x1) = [ 5 * x2 + 7 - ( 5 * x1 + 7) ] / ( x2 - x1) = [ 5 x2 + 7 - 5 x1 - 7 ] / (x2 - x1) = (5 x2 - 5 x1) / ( x2 - x1). We can factor 5 out of the numerator to obtain 5 ( x2 - x1 ) / ( x2 - x1 ) = 5.
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RESPONSE --> I think that I am close I just forgot to use 5 to factor by. But the x1 - x2 did cancel itself out. Right self critique assessment: 2
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22:42:08 `q004. If f(x) = 5x + 7, then for what value of x is f(x) equal to -3?
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RESPONSE --> f(x) = 5x + 7 = -3 f(x) = (5 * -3 ) + 7 = -8 confidence assessment: 1
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22:51:37 If f(x) is equal to -3 then we right f(x) = -3, which we translate into the equation 5x + 7 = -3. We easily solve this equation (subtract 7 from both sides then divide both sides by 5) to obtain x = -2.
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RESPONSE --> I see now where I made my mistake. I subtracted 7 from 5x , and I new better when solving for = -3 self critique assessment: 2
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