He is wrong because as long as they have the same terms/ variables behind the number it doesn’t matter about if it is positive or negative
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5 is a whole number so keep it as 5 then 4 is in the tenths place so that means have ten for the denominator so 5 and 4/10 is the mixed number then simplified to 5 and 2/5
3)
82 + p >= 150
p>= 150 - 82
p>= 68
answer A.
4)
x/-10 > 6
x > -60
answer
x > -60
5)
5z >= - 75
z >= -75/5
z >= -15
answer
z >= -15
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.
