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Consider the function=$${\mathtt{4}}{\mathtt{\,\times\,}}{{\mathtt{x}}}^{{\mathtt{2}}}{\mathtt{\,-\,}}{\mathtt{bx}}{\mathtt{\,\small\textbf+\,}}\left({\mathtt{5}}{\mathtt{\,-\,}}{\mathtt{a}}\right)$$, where a,b are constant

change the function in the form$${{A}{\left({\mathtt{x}}{\mathtt{\,-\,}}{\mathtt{B}}\right)}}^{\,{\mathtt{2}}}{\mathtt{\,\small\textbf+\,}}{\mathtt{C}}$$ where A,B and C are constant

 Jan 15, 2015

Best Answer 

 #1
avatar+130540 
+5

4x^2 - bx + (5 - a)   we need to "complete the square," here.... first, factor out the 4...

4 [ x ^2 - (b/4) x + (5-a)/4]   ...take (1/2) the coefficient on the x term, (b/8), square it, and add and subtract it

4[ x ^2 - (b/4)x + (b^2/64)  + (5-a)/4 - (b^2/64)] =

4[(x - b/8)^2 + (16(5-a) - b^2)/64 ] =

4(x - b/8)^2 + [ (80 - 16a - b^2) / 16 ]

 

 Jan 15, 2015
 #1
avatar+130540 
+5
Best Answer

4x^2 - bx + (5 - a)   we need to "complete the square," here.... first, factor out the 4...

4 [ x ^2 - (b/4) x + (5-a)/4]   ...take (1/2) the coefficient on the x term, (b/8), square it, and add and subtract it

4[ x ^2 - (b/4)x + (b^2/64)  + (5-a)/4 - (b^2/64)] =

4[(x - b/8)^2 + (16(5-a) - b^2)/64 ] =

4(x - b/8)^2 + [ (80 - 16a - b^2) / 16 ]

 

CPhill Jan 15, 2015

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