If
<em>f(x)</em> = <em>ax</em> ³ + <em>bx</em> ² - 5<em>x</em> + 9
then
<em>f '(x)</em> = 3<em>ax </em>² + 2<em>bx</em> - 5
Given that <em>f</em> (-1) = 12 and <em>f</em> '(-1) = 3, we get the system of equations
-<em>a</em> + <em>b</em> + 5 + 9 = 12
3<em>a</em> - 2<em>b</em> - 5 = 3
or
-<em>a</em> + <em>b</em> = -2
3<em>a</em> - 2<em>b</em> = 8
Multiply through the first equation by 2 and add it to the second one to eliminate <em>b</em> and solve for <em>a</em> :
2(-<em>a</em> + <em>b</em>) + (3<em>a</em> - 2<em>b</em>) = 2(-2) + 8
-2<em>a</em> + 2<em>b</em> + 3<em>a</em> - 2<em>b</em> = -4 + 8
<em>a</em> = 4
Substitute this into the first equation above to solve for <em>b</em> :
-4 + <em>b</em> = -2
<em>b</em> = 2
The circumfrence of an 8ft circle is 8 x 3.14 = 25.12ft. Hope this helps!
Answer:
To know how much he bought it for, let's consider the actual amount it be x.
Step-by-step explanation:
10% of x + $585 = x
x/10 + $585 = x
$585 = x-x/10
$585= 9x/10
9x=$5850
x=$5850/9
x=$650
.: the actual price was $650.
Answer:
Length = 9 inches
Step-by-step explanation:
The perimeter of a rectangle is:
perimeter = 2(length + width)
24 = 2(a+b)
a = b + 6
a = length
b = width
then:
24 = 2((b+6)+b)
24/2 = b+6+b
12 = 2b + 6
12-6 = 2b
6 = 2b
b = 6/2
b = 3 inches
a = b+6
a = 3+6
a = 9 inches
Check:
24 = 2(9+3)
24 = 2*12
I know it’s A. But not sure about the fraction part I’ll solve it later for you
