Z varies jointly with x, and y, and z=7 when x= 2, y= 2

56

Step-by-step explanation:

Complete question:

Z varies jointly with x and y , x=2 and y=2, z=7. Find z when x=4 and y=8 using joint variation . (I need the problem worked out step by step)

If z varies jointly with x, and y, this is expressed as;

z = kxy

If z=7 when x= 2, y= 2

7  = k(2)(2)

7 = 4k

k = 7/4

To get z when x= 4 and y = 8

z = kxy

z =7/4 (4)(8)

z = 7*8

z = 56

Hence the value of z is 56

i need more info. are you looked to see there mph? how much they deliver? how far they go?

step-by-step explanation:

see explanation

step-by-step explanation:

a

(6r + 7) + (13 + 7r) ( remove brackets and collect like terms )

= 6r + 7 + 13 + 7r

= 13r + 20

b

remove brackets and collect like terms

13 - r - 1 + r

= 12 - r

c

remove brackets and collect like terms

= - 8 - r + 2r - 4

= - 12 + r

d

remove brackets and collect like terms

= 7r - - - 6r

[-   - = - - = - ]

= r -