Question

y=4x
x+y=5

Answer 1

hello

Answer 2

this is a classic "substituion" problem

Answer 3

the idea is that you want to take the value of a variable from one equation, and "substitute" that into the other

Answer 4

since you have two unknowns, you need two equations - which you have

Answer 5

so let's take y=4x and substitute it into the second equation

Answer 6

so x+y = 5 becomes x + (4x) = 5 (I just replaced y in the second equation with what the first equation asserted y to be)

Answer 7

that is called subsitution

Answer 8

so x+4x =5, 5x=5, and now divide both sides by 5 for the answer

Answer 9

so x = 1

Answer 10

now that you have x, you can substitute that back into either equation to get the value of y

Answer 11

so x+y = 5, and I know that x=1. so 1+y=5, 1-1+y = 5-1, y=4 (subtract 1 from both sides)

Answer 12

i got up to x=1 then got confused on Y

Answer 13

ok great

Answer 14

well, think of x=1 as just another piece of information you now have, along with the original equations

Answer 15

so if x+y = 5 , and I already know x=1, then I can substitute the value of x in that first equation with what I know to be true

Answer 16

so 1 + y = 5

Answer 17

and then y=4

Answer 18

you can always check your work at the end of these problems too

Answer 19

plug in 4x for y

x+4x=5

5x=5

5 divided by 5 = 1

Answer 20

so our guess is that x = 1, and y = 4

Answer 21

if you stick those back into the original equations, do they hold true?

Answer 22

yes

Answer 23

if they do, then you know you did it right

Answer 24

ok. got it. thank u

Answer 25

np!