Math

QuestionFind constants aa and bb for function f(x)f(x) to be continuous everywhere, defined as: f(x)={a+bx,x>23,x=2bax2,x<2 f(x) = \begin{cases} a + b x, & x > 2 \\ 3, & x = 2 \\ b - a x^2, & x < 2 \end{cases}

Studdy Solution

STEP 1

Assumptions1. The function f(x)f(x) is given as a piecewise function with three different expressions for different ranges of xx. . The function is continuous everywhere if it is continuous at every point in its domain.
3. The function is continuous at a point if the limit as xx approaches that point from the left is equal to the limit as xx approaches from the right, and both are equal to the function's value at that point.

STEP 2

To ensure the function is continuous everywhere, we need to ensure it is continuous at x=2x=2. This means the limit as xx approaches2 from the left (using the bax2b-ax^2 expression) must equal the function's value at x=2x=2 (which is), and this must also equal the limit as xx approaches2 from the right (using the a+bxa+bx expression).
So, we have two equations to solve for aa and bblimx2(bax2)=\lim{{x \to2^-}}(b-ax^2) =andlimx2+(a+bx)=\lim{{x \to2^+}}(a+bx) =

STEP 3

Let's first solve the equation for the limit as xx approaches2 from the left.
limx2(bax2)=3\lim{{x \to2^-}}(b-ax^2) =3

STEP 4

Substitute x=2x=2 into the equation.
ba(2)2=3b-a(2)^2 =3

STEP 5

implify the equation.
b4a=3b-4a =3

STEP 6

Now, let's solve the equation for the limit as xx approaches2 from the right.
limx2+(a+bx)=3\lim{{x \to2^+}}(a+bx) =3

STEP 7

Substitute x=2x=2 into the equation.
a+b(2)=3a+b(2) =3

STEP 8

implify the equation.
a+2b=3a+2b =3

STEP 9

Now we have a system of two equations, which we can solve to find the values of aa and bb.
{b4a=3a+2b=3\begin{cases} b-4a =3\\a+2b =3\end{cases}

STEP 10

Multiply the second equation by2 and subtract the first equation from the result to eliminate bb.
2(a+2b)(b4a)=2332(a+2b) - (b-4a) =2 \cdot3 -3

STEP 11

implify the equation to find the value of aa.
a+4bb+8a=63a+4b-b+8a =6-310a+3b=310a+3b =310a=33b10a =3 -3ba=33b10a = \frac{3 -3b}{10}

STEP 12

Substitute aa into the first equation from our system of equations to find bb.
b4(b10)=b -4\left(\frac{ -b}{10}\right) =

STEP 13

implify the equation to find the value of bb.
10b12+12b=3010b -12 +12b =3022b=4222b =42b=4222=.90909b = \frac{42}{22} =.90909

STEP 14

Substitute bb back into the equation for aa to find the value of aa.
a=33.9090910a = \frac{3 -3 \cdot.90909}{10}

STEP 15

Calculate the value of aa.
a=35.7272710=0.272727a = \frac{3 -5.72727}{10} = -0.272727The values of aa and bb that make the function f(x)f(x) continuous everywhere are a=0.272727a = -0.272727 and b=.90909b =.90909.

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