find values? :) (1 Viewer)

[blacktown_]

find values of A, B and C if 4x^2-3x+7 = (Ax+4)^2 + B(x+4) + C

thanks

 

[nightweaver066]

Expand RHS, group terms by degree of x, equate coefficients and solve equations obtained simultaneously.

I'll do the first 2 parts for you.

 

[JT145]

Expand your RHS

Ax^2 +8ax +16 + 4b +c

Group values of x together

Ax^2 + 8Ax + bx + 16+ 4b +c

= Ax^2 + x (8A+b) + 16+ 4b +c
Notice that this now has a resembelance to LHS.

Ax^2 must equal 4x^2. Therefore A =4

(8A+b) = -3
Because A =4
b = -35

16 + 4b + c = 7

16 + 4(-35) + c =7

C = 131.

Not 100% sure if this is correct.... the B and C values seem to be way larger than they should be.

 

[bobmcbob365]

A^2 x^2 =4
not Ax^2 =4

 

[nightweaver066]

Remember that

 

[wannabesurgeon]

A = 2

Remember that

Nightweaver, isn't it +-2? If it isn't why not?

 

[nightweaver066]

Nightweaver, isn't it +-2? If it isn't why not?

Yeah it is, will edit so that further confusion doesn't ensue lol

 

[blacktown_]

thanks heaps everyone