Answer:
x = -7/3 or -5
Step-by-step explanation:
3x^2 + 22x = -35
3x^2 + 22x + 35 = 0
(3x + 7) (x + 5) = 0
so for 3x+7:
3x+7 = 0
3x = -7
x = -7/3
So for x + 5:
x + 5 = 0
x = -5
1.8, Problem 37: A lidless cardboard box is to be made with a volume of 4 m3
. Find the
dimensions of the box that requires the least amount of cardboard.
Solution: If the dimensions of our box are x, y, and z, then we’re seeking to minimize
A(x, y, z) = xy + 2xz + 2yz subject to the constraint that xyz = 4. Our first step is to make
the first function a function of just 2 variables. From xyz = 4, we see z = 4/xy, and if we substitute
this into A(x, y, z), we obtain a new function A(x, y) = xy + 8/y + 8/x. Since we’re optimizing
something, we want to calculate the critical points, which occur when Ax = Ay = 0 or either Ax
or Ay is undefined. If Ax or Ay is undefined, then x = 0 or y = 0, which means xyz = 4 can’t
hold. So, we calculate when Ax = 0 = Ay. Ax = y − 8/x2 = 0 and Ay = x − 8/y2 = 0. From
these, we obtain x
2y = 8 = xy2
. This forces x = y = 2, which forces z = 1. Calculating second
derivatives and applying the second derivative test, we see that (x, y) = (2, 2) is a local minimum
for A(x, y). To show it’s an absolute minimum, first notice that A(x, y) is defined for all choices
of x and y that are positive (if x and y are arbitrarily large, you can still make z REALLY small
so that xyz = 4 still). Therefore, the domain is NOT a closed and bounded region (it’s neither
closed nor bounded), so you can’t apply the Extreme Value Theorem. However, you can salvage
something: observe what happens to A(x, y) as x → 0, as y → 0, as x → ∞, and y → ∞. In each
of these cases, at least one of the variables must go to ∞, meaning that A(x, y) goes to ∞. Thus,
moving away from (2, 2) forces A(x, y) to increase, and so (2, 2) is an absolute minimum for A(x, y).
Answer:
-2/9
Step-by-step explanation:
First, you have to set a system of equations to determine the number of fiction and of nonfiction books.Call f the number of fiction books and n the number of nonfiction books. Then 400 = f + n. And f = n + 40 => n = f - 40 => 400 = f + f - 40 => 400 - 40 = 2f => f = 360 / 2 = 180. Now to find the probability of picking two fiction books, take into account the the Audrey will pick from 180 fiction books out of 400, and Ryan will pick from 179 fiction books out of 399, so the probability will be<span> (180/ 400) * (179/399) = 0.20 (rounded to two decimals). Answer: 0.20</span>
Answer:
a = $13.5
Step-by-step explanation:
Let a = adult tickets
Let c = children tickets
Translating the word problem into an algebraic equation;
<u>For the Martinez family;</u>
2a + 3c = $60
<u>For the Wright family;</u>
3a + 5c = $95.5
Thus, the simultaneous equations are;
..........equation 1
.........equation 2
We would use substitution method to solve;
From equation 2, we make a the subject of formula;
3a = 95.5 - 5c
a = (95.5 - 5c)/3
<em>Substituting the value of "a" into equation 1, we have;</em>
2[(95.5-5c)/3] + 3c = 60
Multiplying all through by 3;
2(95.5 - 5c) + 9c = 180
191 - 10c + 9c = 180
191 - c = 180
c = 191-180
c = $11
To find the value of a;
2a +3c = 60
<em>Substituting the value of "c" into the equation, we have;</em>
a = $13.5
<em>Therefore, the cost of an adult movie ticket is $13.5. </em>