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anonymous
 5 years ago
Find the vertex and all intercepts of the quadratic function f(x) = –2x2 + 12x – 15.I need to review for a test, plz help
anonymous
 5 years ago
Find the vertex and all intercepts of the quadratic function f(x) = –2x2 + 12x – 15.I need to review for a test, plz help

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amistre64
 5 years ago
Best ResponseYou've already chosen the best response.1the vertex x compnent is 12/4 = 3; use that value to determine the y component teh rest is either complete the square, or quadrtic formula it... you get the same results

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0where you get 12/4=3?

amistre64
 5 years ago
Best ResponseYou've already chosen the best response.1ok.... lets do it this way; we want the first# to be 1; so divide it all by 2: y = x^2 6x +15/2 = 0 for simplicities sake x^2 6x + ___ = 15/2 ; we subtracted 15/2; now we wanna complete the square on the left side we complete the square by making it a perfect square; so we need a number that when added to itself makes 6; then we can square that number to complete it :) x^2 6x + ___ = 15/2 3 + 3 = 6; 3(3) = 9, lets use 9 to fill in the blank x^2 6x +9 = 15/2 +9 ; we added 9 to each side, now convert the left side to its perfect square look, and add the rightside together like this: (x3)^2 = 3/2 ; now sqrt both sides x3 = + sqrt(3/2) ; now add 3 to both sides to get x = 3 + sqrt(3/2) ; and dbl chech to make sure I didnt mess it up lol

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0you did the whole problem their?

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0you did the whole problem their?

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0you did the whole problem their?

amistre64
 5 years ago
Best ResponseYou've already chosen the best response.1the first number there is the vertexes 'x' component; use it to find the 'y' component. the roots are simply what x =: x = 3 + sqrt(3/2) AND x = 3  sqrt(3/2)

amistre64
 5 years ago
Best ResponseYou've already chosen the best response.1another way would be to solve it for the geometric interpretation of the equation; which is similar except we dont use =0, we use =y y = –2x2 + 12x – 15 (1/2)y = x^2 6x +15/2 (1/2)y 15/2 = x^2 6x 16y/2 +9 = x^2 6x +9 4y +9 = (x3)^2 4(y  9/4) = (x3)^2 vertex = (3, 9/4)

amistre64
 5 years ago
Best ResponseYou've already chosen the best response.116/2 = 8 lol i forgot how to divide by 2 :)

amistre64
 5 years ago
Best ResponseYou've already chosen the best response.18y +9 = (x3)^2 8 (y  9/8) = (x3)^2; vertex = (3, 9/8) ?? lets check: –2(3)^2 + 12(3) – 15 = y 18 15 +36 = y 33 + 36 = y 3 = y .... well, I got the x right lol

amistre64
 5 years ago
Best ResponseYou've already chosen the best response.1my mistake was thinking I could combine y/2 and 15/2 .... silly me

amistre64
 5 years ago
Best ResponseYou've already chosen the best response.1(1/2)y 15/2 +9 = x^2 6x +9 (1/2)y +3/2 = (x3)^2 (1/2) (y3) = (x3)^2 vertex = (3,3) that did it ...
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