substitution method?

Question

my problem reads: 4x+3y=11
x=59-7y

Any help on how i can solve this. any help would be great!!

ok i have another tricky one. my problem reads :x-10y=-20
9y-2x=29

Any help on this would be great again!!

Answer 1

1)Just take the x=59-7y and replace it for x:
4(59-7y)+3y=11
236-28y+3y=11
-25y+236=11
-25y=-225
y=9

x=59-7(9)
x=59-63
x=-4

The solution set is (-4,9)

Check:
-4=59-7(9)
-4=59-63
-4=-4

4(-4)+3(9)=11
-16+27=11
11=11

2)
x-10y=-20
9y-2x=29

Take the first equation and add 10y from both sides:
x=10y-20
Replace it for x in the next equation:
9y-2(10y-20)=29
9y-20y+40=29
-11y+40=29
-11y=-11
y=1

9(1)-2x=29
9-2x=29
-2x=20
x=-10

The solution set is (-10,1)

Check:
-10-10(1)=-20
-10-10=-20
-20=-20

9(1)-2(-10)=29
9+20=29
29=29

I hope this helps!

Answer 2

Just put the value of x in the the formula.

4x+3y=11
x=59-7y
thus

4(59-7y)+3y=11

Then solve that as an equilateral equation.

The answer should be y=9

Answer 3

you just replace x on the first equation by 59-7y
therefore 4(59-7y)+3y=11
distribute 236-28y+3y=11
236-25y=11
subtract both sides by 236
-25y=-225
divide both sides by -25
therefore y=(-225)/-25= 9
put y=9 into second equation to find x
x=59-7*9=59-63= -4
the solution is x= -4 and y=9
good luck

Answer 4

Substitue (i.e. replace) the x in 4x+3y=11 with 59-7y

4(59-7y)+3y=11

Multiply the 4 across each term in 59-7y...

236 - 28y + 3y = 11

Can you figure out the rest?