Given the system of equations. which of the options represents the resulting equation after an equivalent expression for y is substituted into the second equation. (see picture.) a) 2x - (4x + 3) = 12 b) -4x + 4x - 3 = 3 c) 2 (4x + 3) - y d) -4(4y + ) + y = 3

By using method of substitution we need to solve one equation for a variable and plug in that equation in the second equation.

Let's solve the first equation for y of the given system of equation.

So, -4x+y=3

4x-4x+y=4x+3 Add 4x to each sides of the equation.

y= 4x+3.

Next step is to plug in 4x+3 for y in the second equation. Hence, after substituting we will get:

2x-(4x+3)=12.

Hence the correct choice is A) 2x - (4x + 3) = 12.

hello from mrbilldoesmath!

answer:

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

discussion:

the trick is to recognize that 343 = 7^3 and 216 = 6^3 and, in general,

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

in our case

343x^3+216y^3   =   (7x)^3 + (6y)^3

so take a = 7x and b = 6y in the above equation to get the answer.

you,

mrb