Answer:
D.) c is multiplied by 4
Step-by-step explanation:
If a is doubled, it becomes 2a. If b is doubled, it becomes 2b. Now we replace a with 2a and b with 2b and simplify.
Answer: D.) c is multiplied by 4
A. ratio of areas = 2^2 /5^2 = 4/25
B 14^2 : 1 = 196:1
C. ratio of perimeters would be sqrt81 = 9 times
The true answer is A. all parallelograms are rectangles
Real world problem for 11x = 385
Sam brought home 385 packs of string for the party. At the party, Sam invites 11 people, and wants to give each person the same amount of string. How much string does each person get?
Answer:
x = 10 cm, y = 5 cm gives a minimum area of 300 cm^2.
Step-by-step explanation:
V= x^2y = 500
Surface area A = x^2 + 4xy.
From the first equation y = 500/x^2
So substituting for y in the equation for the surface area:
A = x^2 + 4x * 500/x^2
A = x^2 + 2000/x
Finding the derivative:
dA/dx = 2x - 2000x^-2
dA/dx = 2x - 2000/x^2
This = 0 for a minimum/maximum value of A, so
2x - 2000/x^2 = 0
2x^3 - 2000 = 0
x^3 = 2000/ 2 = 1000
x = 10
Second derivative is 2 + 4000/x^3
when x = 10 this is positive so x = 10 gives a minimum value of A.
So y = 500/x^2
= 500/100
= 5.
