Question

y = 3x + 4
2x + 3y = 10

Which of the following steps could be used to solve by substitution?

3x + 4 = 2x + 3y
2x + 3(3x + 4) = 10
2(3x + 4) + 3y = 10
3(y = 3x + 4)

Answer 1

Hint:

\[
\Large {\color{red}{y}} = 3x+4\\
\Large 2x + 3{\color{red}{y}} = 10
\]

Answer 2

@jim_thompson5910 i dont get the hint..

Answer 3

the two 'y's are the same, so you can replace the 3y in the second equation with 3(...)

the dot dot dot is whatever y is equivalent to

Answer 4

example

\[
\Large \color{red}{y} = x+2\\
\Large 5x + 10\color{red}{y} = 17
\]

After substitution, we get

\[
\Large 5x + 10\color{red}{y} = 17\\
\Large 5x + 10(\color{red}{y}) = 17\\
\Large 5x + 10(\color{red}{x+2}) = 17
\]

Answer 5

@jim_thompson5910 could you possibly tell me what you got so i can see how you got it

Answer 6

do you see in my example how I replaced y with x+2 ?

Answer 7

@jim_thompson5910 i suck @ math and this my last answer on my homework

Answer 8

all you're doing is replacing y with what it is equivalent to. Look back at my example again

Answer 9

In my example, y is equivalent to x+2

so that's how I replaced the y with x+2 in the second equation. Don't forget the parenthesis

Answer 10

It's B because \[2x+3(3x+4)=10\]can be substituted to \[5x+7=10\]and this is the substitution property.

Answer 11

The first equation shows what y is equal to. \[y=3x+4\]
So, in the second equation, you can put what the y was equal to in the place of where the y was.
\[2x+3y=10\]
\[2x+3(3x+4)=10\]