i. The Lagrangian is

with critical points whenever



- If
, then
. - If
, then
. - Either value of
found above requires that either
or
, so we get the same critical points as in the previous two cases.
We have
,
,
, and
, so
has a minimum value of 9 and a maximum value of 182.25.
ii. The Lagrangian is

with critical points whenever
(because we assume
)



- If
, then
. - If
, then
, and with
we have
.
We have
,
,
, and
. So
has a maximum value of 61 and a minimum value of -60.
Answer:
Demand is Elastic when Price > 200 ; Demand is inelastic when Price < 200
Step-by-step explanation:
p = 400 - 4x
4x = 400 - p
x = (400 - p) / 4 → x = 100 - p/4
Elasticity of demand [ P ed ] = (Δx / Δp) x (p / x)
Δx / Δp [Differentiating x w.r.t p] = 0 - 1/4 → = -1/4
P ed = <u>-1</u> x<u> p </u>
4 (400 - p)/4
= <u>-1</u> x <u> 4p </u> = -p / (400-p)
4 (400 - p)
Price Elasticity of demand : only magnitude is considered, negative sign is ignored (due to negative price demand relationship as per law of demand).
So, Ped = p / (400 - p)
Demand is Elastic when P.ed > 1
p / (400-p) > 1
p > 400 - p
p + p > 400 → 2p > 400
p > 400 / 2 → p > 200
Demand is inelastic when P.ed < 1
p / (400-p) < 1
p < 400 - p
p + p < 400 → 2p < 400
p < 400 / 2 → p < 200
Start by writing your own expression.
x is the smaller number and x + 1 is the next number
x(x + 1) = 420
x^2 + x - 420 =0 ⇒ constant = -420