Answer:
x=-6 y=-26
Step-by-step explanation:
in the first is -4 every time, in the second is -20 every time
The function, as presented here, is ambiguous in terms of what's being deivded by what. For the sake of example, I will assume that you meant
3x+5a
<span> f(x)= ------------
</span> x^2-a^2
You are saying that the derivative of this function is 0 when x=12. Let's differentiate f(x) with respect to x and then let x = 12:
(x^2-a^2)(3) -(3x+5a)(2x)
f '(x) = ------------------------------------- = 0 when x = 12
[x^2-a^2]^2
(144-a^2)(3) - (36+5a)(24)
------------------------------------ = 0
[ ]^2
Simplifying,
(144-a^2) - 8(36+5a) = 0
144 - a^2 - 288 - 40a = 0
This can be rewritten as a quadratic in standard form:
-a^2 - 40a - 144 = 0, or a^2 + 40a + 144 = 0.
Solve for a by completing the square:
a^2 + 40a + 20^2 - 20^2 + 144 = 0
(a+20)^2 = 400 - 144 = 156
Then a+20 = sqrt[6(26)] = sqrt[6(2)(13)] = 4(3)(13)= 2sqrt(39)
Finally, a = -20 plus or minus 2sqrt(39)
You must check both answers by subst. into the original equation. Only if the result(s) is(are) true is your solution (value of a) correct.
7(x-2) + 3(x + 2) = 5(x-6)...distribute thru the parenthesis
7x - 14 + 3x + 6 = 5x - 30...combine like terms
10x - 8 = 5x - 30...subtract 5x from both sides
10x - 5x - 8 = -30....add 8 to both sides
10x - 5x = -30 + 8...combine like terms
5x = - 22
x = -22/5 = - 4 2/5 <==
(17/70)x = 70/70(17x)/70 = 70/7017x = 70x = 70/17x ≈ 4.1176
Answer:
D is true
Step-by-step explanation:
Hope it helps!
