You are given the system of equations to solve by the elimination method, which is an incorrect step that will not produce a system with the same solution? x + 2y = 7 2x − 5y = 5 a) add 5 times the first equation and 2 times the second equation b) multiply the first equation by 2 and subtract the second equation c) multiply the first equation by −2 and add the second equation d) multiply x by 2 in the first equation and subtract the second equation

D

Step-by-step explanation:

If you're doing to multiply a value by a number, ALL terms in the equation must be multiplied by the same value otherwise you do not have a correct equation.

D) multiply x by 2 in the first equation and subtract the second equation

Step-by-step explanation:

When you are trying to solve a system of equations you have to eliminate one of the terms so you´ll end up with only a one term equation that is solvave, in this case if you multiply X by 2 you can actually eliminate X from that equation, but by not multiplying all the terms on the equation you end up with a whole different equation and the result wont be accurate.

let's add {f(x)=x+1}f(x)=x+1 and {g(x)=2x}g(x)=2x together to make a new function.

f(x)+g(x) =(x+1)+(2x)=x+1+2x=3x+1

let's call this new function hh. so we have:

{h(x)}={f(x)}+{g(x)}{=3x+1}h(x)=f(x)+g(x)=3x+1

we can also evaluate combined functions for particular inputs. let's evaluate function hh above for x=2x=2. below are two ways of doing this.

method 1: substitute x=2x=2 into the combined function hh.

h(x)

h(2)

​    

=3x+1

=3(2)+1

=7

​ since h(x)=f(x)+g(x)h(x)=f(x)+g(x), we can also find h(2)h(2) by finding f(2) +g(2)f(2)+g(2).

first, let's find f(2)f(2):

f(x)

f(2)

​    

=x+1

=2+1

=3

​  

now, let's find g(2)g(2):

g(x)

g(2)

​    

=2x

=2⋅2

=4

​  

so f(2)+g(2)=3+4=\greend7f(2)+g(2)=3+4=7.

notice that substituting x =2x=2 directly into function hh and finding f(2) + g(2)f(2)+g(2) gave us the same answer!