What does the below simultaneous equation equal to and why?

Question

I know there are three methods when using simultaneous equations: elimination, substitution and graph.However, I don't know the answer to the following:

7x - 5y = - 1
3y = 4x

The person to give me the correct answer along with working out gets 10 points!

PS. I understand the concept but this equation is kind of new to me.

Thanks

Answer 1

7x - 5y = - 1 ----------------(1)
3y = 4x ==> 4x - 3y = 0 -----------------(2)
{(1)*3} - {(2)*5} gives x = -3
Now, plug this value in the second equation, we get y = -4

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Answer 2

From the second equation, we can see that
x = 3y/4. If we now substitute this into the first equation we get

(21y/4) - 5y = -1 We can now re-write -5y as -20y/4 so now we have:

(y21y/4) - (20y/4) = -1 or y/4 = -1. Multiply both sides by 4
gives us : y = - 4.

Put this in the second equation we get: -12 = 4x.
Divide both sides by 4 gives x = -3
This can be verified by putting the numbers into each equation.
If you do, don't forget minus minus is a plus!

Answer 3

First of all, all the x's and y's must be put on the same side so,
7x - 5y = -1
-4x + 3y = 0

21x - 15y = -3
-20x + 15y = 0

x=-3

7x - 5y = -1
7(-3) - 5y = -1
-21 - 5y = -1
-5y = -1 + 21
-5y = 20
-y = 4
y = -4

(-3,-4)

Hope this helps

Answer 4

7x - 5y = -1
-4x + 3y = 0
Elimination is easiest: multiply top row by 4 and bottom by 7 to eliminate x:
28x - 20y = -4
-28x+21y = 0

that comes out y = -4; then plug that in to each equation to get x (should be the same both times)

Answer 5

7x-5y=-1 (1)
3y=4x
therefore y=(4/3)*x (2)

Substituting (2) into (1) gives

7x-(5*(4/3)*x)=-1

7x-((20/3)*x)=-1 ie (7-6.66)x=-1

0.33x=-1
therefore
x=-3

3y=4x therefore
y =-12/3

y= -4, x= -3

Answer 6

7x - 5y = -1
4x - 7y = 0

NB multiply top eq'n by -7 and bottom eq'n by +5. We have;_

-49x + 35y = 7
20x - 35y = 0

Add both eq'n together

-29x = 7
x = 7/-29 (-0.24137931)
Substitute this value for 'x' into one of the eq'ns.

7(7/-29) - 5y = -1
49/-29 - 5y = -1
5y = 49/-29 + 1
y = (49/-29 + 1)/5
y = [(-49 + 29)/29]/5
y = [-20/29]/5
y = -20/145
y = -4/29 ( -0.137931034)

Answer 7

I'm almost sure this was a question in the SATS or there was a one similar. Ill try and work it out.

4x/3y=
x= 0.75y

7x - 5y =-1
(7*1) - (5*0.75)=-1
7- 3.75=3.25

It doesn't. But then again I could never do algebra.

Answer 8

7x - 5y = - 1 <-- Eq1
3y = 4x <-- Eq2
Solve Eq 2 for y getting y = 4x/3
Now plug this in Eq 1 getting :
7x - 5(4x/3) = -1
7x -20x/3 = -1
21x/3 -20x/3 = -1
x/3 = -1
x = - 3
3y = 4*-3
y = -4

Answer 9

from 3y=4x you get y=4/3 *x
so
7x -20/3*x=-1
so 21/3/ x-20/3 x= -1 and x= -3 and y = -4

Answer 10

those 2 strains has no answer at the same time as both strains are parallel. 2x-ky = 2 or equivalent to ky = 2x-2 then m1 = 2/ok 3x+(ok+a million)y = 4 or equivalent to (ok+a million)y = 4-3x then m2 = (-3)/(ok+a million) If m1 = m2 2/ok = (-3)/(ok+a million) 2k+2 = -3k ok = 2/5