Monday, February 1, 2016

Given the system of equations 4x-y=-5 2(x-1)=3(y+1) verify if x^3>y^3?

To verify if the cube of x is larger than the cube of y,
we need to determine the values of x and y, therefore, we'll have to solve the
system.


We'll use substitution method. We'll re-write the
first equation, isolating y to the left side:


-y = -4x -
5


y = 4x + 5


We'll re-write
the 2nd equation in terms of x:


2(x-1) = 3(4x + 5 +
1)


We'll remove the
brackets:


2x - 2 = 12x +
18


We'll isolate the terms in x to the left
side:


2x - 12x = 18 + 2


-10x =
20


x = -2


We'll determine
y:


y = 4*(-2) + 5


y = -8 +
5


y = -3


We'll raise to cube
the values of x and y:


`x^3 =
(-2)^3`


`x^3 = -8`


`y^3 =
(-3)^3`


`y^3 =
-27`


We notice that -8 > -27,
therefore the inequality `x^3 > y^3` is
verified.

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