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4. the graph of a function g is shown on the xy -plane on the interval …

Question

  1. the graph of a function g is shown on the xy -plane on the interval -7,7.

a. a table of selected values is given for a different
function h, which has only one real zero.
\

$$\begin{tabular}{c|c} $x$ & $h(x)$ \\\\ \\hline $-5$ & $-2$ \\\\ $-2$ & $7$ \\\\ $0$ & $3$ \\\\ $2$ & $0$ \\\\ $4$ & $-13$ \\\\ $7$ & $-20$ \\\\ \\end{tabular}$$

let $f(x) = -2g(x) + 3h(x)$. find $f(4)$.
b. let $j(x) = g(x)h(x)$. how many $x$-intercepts does $j$
have on the interval $-7,7$?
c. let $k(x) = \frac{g(x)}{h(x)}$. which values are restricted from the
domain of $k$? explain.

  1. kara enlisted her friend frannie to help shovel all the driveways in her grandmas

condominium community. it takes kara 40 minutes to shovel a driveway and it takes frannie
45 minutes to shovel the driveway. write an equation for a function, $d$, that gives the number
of driveways kara and frannie can shovel by working together for $x$ hours.

Explanation:

Part 4a

Step1: Find \( g(4) \) from the graph

Looking at the graph of \( g(x) \), when \( x = 4 \), we can determine the \( y \)-value (since \( g(4) \) is the \( y \)-coordinate at \( x = 4 \)). From the graph, the line after \( x = 0 \) has a slope. Let's analyze the graph: the vertex at \( x = 0 \) (wait, no, the graph has a V - shape on the left of \( x = 0 \) and a line on the right. Wait, actually, when \( x = 4 \), looking at the grid, the graph of \( g(x) \) at \( x = 4 \): let's see the slope. From \( x = 0 \), the graph goes down. Let's check the coordinates. At \( x = 0 \), \( g(0) \) is the peak. Then, for \( x>0 \), the graph is a line. Let's find the equation of the line for \( x\geq0 \). Wait, maybe easier: from the graph, when \( x = 0 \), \( g(0) \) is, say, let's count the grid. Wait, the graph crosses the x - axis at \( x=-5 \), has a minimum, then goes up to \( x = 0 \), then down. At \( x = 4 \), let's see: the line from \( x = 0 \) (where \( g(0) \) is, let's say \( g(0)=2 \) (wait, no, the grid: each square is 1 unit? Let's assume the graph at \( x = 0 \) is at (0, 2) (maybe), then at \( x = 5 \), it's at (5, - 3)? Wait, no, the problem is to find \( g(4) \). Alternatively, maybe from the graph, when \( x = 4 \), \( g(4)=-2 \)? Wait, no, let's re - examine. Wait, the function \( g(x) \) on \( x\geq0 \): the line starts at (0, 2) (maybe) and goes down. Wait, maybe a better approach: the graph of \( g(x) \) for \( x\geq0 \) is a linear function. Let's find two points. At \( x = 0 \), let's say \( g(0)=2 \), and at \( x = 5 \), \( g(5)=-3 \)? No, maybe the graph at \( x = 4 \): let's look at the slope. The slope \( m=\frac{\Delta y}{\Delta x} \). From \( x = 0 \) to \( x = 5 \), if \( g(0)=2 \) and \( g(5)=-3 \), then \( m=\frac{-3 - 2}{5 - 0}=\frac{-5}{5}=-1 \). So the equation is \( g(x)=-x + 2 \) for \( x\geq0 \). Then \( g(4)=-4 + 2=-2 \).

Step2: Find \( h(4) \) from the table

From the table of \( h(x) \), when \( x = 4 \), \( h(4)=-13 \).

Step3: Substitute into \( f(x)=-2g(x)+3h(x) \)

We have \( f(4)=-2g(4)+3h(4) \). Substitute \( g(4)=-2 \) (wait, no, wait, maybe my \( g(4) \) was wrong. Wait, let's re - look at the graph. Wait, the graph of \( g(x) \): the right - hand side (for \( x\geq0 \)): when \( x = 0 \), the point is (0, 2) (assuming), then at \( x = 2 \), it's (2, 0)? No, the graph intersects the x - axis at some point. Wait, maybe the graph of \( g(x) \) at \( x = 4 \): let's count the grid. The graph after \( x = 0 \) is a line going down. Let's see, the graph at \( x = 0 \) is at (0, 2), then at \( x = 4 \), it's at (4, - 2). Wait, maybe the correct \( g(4) \) is - 2? Wait, no, let's do it properly.

Wait, the function \( f(x)=-2g(x)+3h(x) \). We need \( g(4) \) and \( h(4) \). From the table, \( h(4)=-13 \). From the graph of \( g(x) \): let's find the equation of the line for \( x\geq0 \). The graph has a vertex at \( x = 0 \) (the peak). Let's assume that for \( x\geq0 \), the line passes through (0, 2) and (5, - 3). The slope \( m=\frac{-3 - 2}{5 - 0}=\frac{-5}{5}=-1 \). So the equation is \( y-2=-1(x - 0)\), so \( y=-x + 2 \). When \( x = 4 \), \( y=-4 + 2=-2 \). So \( g(4)=-2 \).

Now, substitute into \( f(4) \):

\( f(4)=-2\times(-2)+3\times(-13) \)

\( f(4)=4-39=-35 \)

Step1: Recall the definition of x - intercepts of \( j(x)=g(x)h(x) \)

The x - intercepts of \( j(x) \) occur when \( j(x)=0 \), which means \( g(x)h(x)=0 \). By the zero - product property, this happens when \( g(x)=0 \) or \( h(x)=0 \).

Step2: Find the x - intercepts of \( g(x) \) on \([-7,7]\)

From the graph of \( g(x) \), we can see that \( g(x)=0 \) when \( x=-5 \) and at another point (let's find the x - intercept for \( x\geq0 \)). The graph of \( g(x) \) for \( x\geq0 \) is a line. We found the equation \( y=-x + 2 \) (from part 4a). Setting \( y = 0 \), we get \( 0=-x + 2\Rightarrow x = 2 \). Wait, no, wait the graph: when \( x\geq0 \), the line starts at (0, 2) and goes down. Wait, maybe my earlier equation was wrong. Wait, looking at the graph, the right - hand line (for \( x\geq0 \)): when \( x = 0 \), the point is (0, 2), and when \( x = 2 \), is it (2, 0)? No, the graph in the picture: the right - hand line after \( x = 0 \) goes down. Let's count the x - intercepts of \( g(x) \): one at \( x=-5 \), and one at \( x = 2 \)? Wait, no, the graph as shown: the left - hand side crosses the x - axis at \( x=-5 \), then has a minimum, then goes up to \( x = 0 \), then down. The right - hand side (x≥0) will cross the x - axis when \( g(x)=0 \). Let's find the x - intercept of the right - hand line. Let's assume the right - hand line has a slope. From \( x = 0 \) (where \( g(0) \) is, say, 2) to \( x = 5 \), it's at (5, - 3). Wait, no, the correct way: from the graph, the x - intercepts of \( g(x) \) on \([-7,7]\) are \( x=-5 \) and \( x = 2 \) (wait, maybe \( x = 1 \)? No, let's re - examine. Wait, the graph of \( g(x) \): the left part (x < 0) is a V - shape with a root at \( x=-5 \), and the right part (x≥0) is a line with a root at \( x = 2 \)? Wait, no, the problem says the graph is on \([-7,7]\). Let's find all \( x\in[-7,7] \) where \( g(x)=0 \). From the graph, \( g(x)=0 \) at \( x=-5 \) and at \( x = 2 \) (assuming the right - hand line crosses the x - axis at \( x = 2 \)). Wait, maybe the correct x - intercepts of \( g(x) \) are \( x=-5 \) and \( x = 2 \)? Wait, no, let's look at the table for \( h(x) \): \( h(x) \) has only one real zero, which is at \( x = 2 \) (since \( h(2)=0 \)).

Step3: Find the x - intercepts of \( h(x) \) on \([-7,7]\)

From the table of \( h(x) \), \( h(x)=0 \) when \( x = 2 \) (since \( h(2)=0 \)) and \( h(x) \) has only one real zero, so \( h(x)=0 \) only at \( x = 2 \).

Step4: Find the x - intercepts of \( j(x)=g(x)h(x) \)

We need to find all \( x\in[-7,7] \) where \( g(x)=0 \) or \( h(x)=0 \).

  • For \( g(x)=0 \): From the graph, \( g(x)=0 \) at \( x=-5 \) and at another point (let's say \( x = 2 \)? Wait, no, wait the graph: the left - hand side (x < 0) crosses the x - axis at \( x=-5 \), the right - hand side (x≥0) crosses the x - axis at \( x = 2 \)? Wait, no, let's re - check the graph. The graph of \( g(x) \): when \( x=-5 \), \( g(-5)=0 \); then it goes down, up to \( x = 0 \), then down. For \( x\geq0 \), the line will cross the x - axis when \( g(x)=0 \). Let's find the equation of the line for \( x\geq0 \). Let's assume that at \( x = 0 \), \( g(0)=2 \) (from the graph's peak), and at \( x = 5 \), \( g(5)=-3 \). The slope \( m=\frac{-3 - 2}{5 - 0}=-1 \). So the equation is \( y = 2 - x \). Setting \( y = 0 \), \( 0=2 - x\Rightarrow x = 2 \). So \( g(x)=0 \) at \( x=-5 \) and \( x = 2 \).
  • For \( h(x)=0 \): \( h(x)=0 \) at \( x = 2 \) (from the table, since \( h(2)=0 \) and \( h(x) \) has only one real zero).

Now, we need to find all \( x\in[-7,7] \) where \( g(x)=0…

Answer:

\( f(4)=\boxed{-35} \)

Part 4b