The first equation has y=10-2.2x
Substituting that value for y into the second equation:
5x + (10-2.2x)=70
5x + 10-2.2x=70
combining...
2.8x=60
x=?
Plug that value for x into the first equation to find y.
Could someone please help me.
Solve the linear equation by substitution.
Y=10-2.2x
5x+y=70
For the first equation I am getting x=21.4 and for the second equation I am getting y=-37. The answers are 21 3/7 and -37 1/7. Could you show me how you do this so I can see where I went wrong in my steps! Thank you
2 answers
Cherie,
You are using decimals and rounding off your answer before you are substituting.
look at Quidditch's last line
2.8x = 60
x = 60/2.8 = 600/28 = 150/7 or 21 3/7
now y = 10 - 2.2(150/7)
= 10 - (22/10)(150/7)
= 10 - 330/7
= -260/7 or -37 1/7
since "anything"/7 is a repeating decimal, you will never get the "exact" answer by using decimals, you have to keep working in fractions
You are using decimals and rounding off your answer before you are substituting.
look at Quidditch's last line
2.8x = 60
x = 60/2.8 = 600/28 = 150/7 or 21 3/7
now y = 10 - 2.2(150/7)
= 10 - (22/10)(150/7)
= 10 - 330/7
= -260/7 or -37 1/7
since "anything"/7 is a repeating decimal, you will never get the "exact" answer by using decimals, you have to keep working in fractions