Y = x - 1 x + 4y = 16
Im having troubles. Can some 1 explain in complete explanations and all expressions.

{x,y} = {4, -3}

Substitution :

// Solve equation [2] for the variable  x  

 [2]    x = 4y + 16

// Plug this in for variable  x  in equation [1]

  [1]    (4y+16) + y = 1

  [1]    5y = -15

// Solve equation [1] for the variable  y  

  [1]    5y = - 15

  [1]    y = - 3

// By now we know this much :

   x = 4y+16

   y = -3

// Use the  y  value to solve for  x  

   x = 4(-3)+16 = 4

answer: c

because if you look at the chart you can see a pattern and compare it to the question he simplify out your

but i think the formula is f(x)=6x

hello from mrbilldoesmath!

answer:   (7x + 6y) ( 49x^2 - 42xy + 36y^2)

discussion:

in general, the factorization of a^3 + b^3 is

a^3 + b^ 3 = (a + b) ( a^2 - ab + b^2)

in our case note that 343 = 7^3 and 216 = 6^3 so the equation becomes:

343x^3 + 216y^3 = (7x)^3 + (6y)^3

if you think of a (above) as 7x and b as 6y the factorization becomes

343x^3 + 216y^3 =

((7x + 6y) (   (7x)^2 - 7x*6y + (6y)^2)   =

(7x + 6y) ( 49x^2 - 42xy + 36y^2)

you,

mrb

(a + b) (a^2 - a b + b^2)