If y ∝ and y = 4 when x = 2.5, find : (a) y when x = 20

(b) x when y = 5

Step-by-step explanation:

Y = k1/x

4 = k 1/2.5

2.5 x 4 = k

10 = k

Now using this equation we will find the other answers

A) find y when x = 20

Y = k 1/x

Putting values

= 10(1/20) = 1/2 = 0.5

B) find x when y = 5

Y = k 1/x

Putting values

5 = 10 1/x

5x = 10

x = 10/5 = 2

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step-by-step explanation:

(0,-3) see attached graph

step-by-step explanation:

a. to solve the system, graph the two equations.

x = y+3 becomes y=x-3 has m=1/1 and b=-3. start at (0,-3) on the y-axis and plot a point. then move up 1 unit and 1 unit to the right. plot a point and connect.

y=-4x+3 has m =-4/1 and b=-3. start at (0,-3) on the y-axis and plot a point. then move down four units and to the right 1 unit. plot a point and connect.

the solution is the point (x,y) where the two lines intersect. by the graph below it is (0,-3).

b. to solve by substitution, substitute y = -4x-3 into x= y+3

x= (-4x-3) +3

x=-4x

5x=0

x=0

now substitute x = 0 back in to find y.

y= -4(0)-3

y=0-3

y=-3

solution is (0,-3)

c. use elimination by adding the equations together.

x-y=3

4x+y=-3

5x=0

x=0

then substitute into one equation to find y.

y=-4(0)-3

y=-3