Plot the x- and y- intercepts of the function.
1 answer:
Answer:
y intercept = -2
x intercepts = -2,-1,1
Step-by-step explanation:
f(x) = x^3 + 2x^2 -x-2
Set this equation equal to zero to find the x intercepts.
Factoring by grouping
0 =x^3 -x +2x^2 -2
= x( x^2-1) +2(x^2-1)
Factoring out the (x^2-1)
0= (x^2-1) (x+2)
Factoring the first term using the difference of squares (a^2-b^2) = (a-b)(a+b)
0 = (x-1) (x+1) (x+2)
Using the zero product property
x-1 = 0 x+1 = 0 x+2 =0
x=1, x=-1 x=-2
The x intercepts are -2, -1, 1
To find the y intercepts, set x=0
y = x^3 + 2x^2 -x-2
y = 0 -2
y = -2
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<h3>Answer:</h3>
- <u>20</u> kg of 20%
- <u>80</u> kg of 60%
I like to use a little X diagram to work mixture problems like this. The constituent concentrations are on the left; the desired mix is in the middle, and the right legs of the X show the differences along the diagonal. These are the ratio numbers for the constituents. Reducing the ratio 32:8 gives 4:1, which totals 5 "ratio units". We need a total of 100 kg of alloy, so each "ratio unit" stands for 100 kg/5 = 20 kg of constituent.
That is, we need 80 kg of 60% alloy and 20 kg of 20% alloy for the product.
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<em>Using an equation</em>
If you want to write an equation for the amount of contributing alloy, it works best to let a variable represent the quantity of the highest-concentration contributor, the 60% alloy. Using x for the quantity of that (in kg), the amount of copper in the final alloy is ...
... 0.60x + 0.20(100 -x) = 0.52·100
... 0.40x = 32 . . . . . . . . . . .collect terms, subtract 20
... x = 32/0.40 = 80 . . . . . kg of 60% alloy
... (100 -80) = 20 . . . . . . . .kg of 20% alloy