$\bf 5n^2+6n+7=n^2-4n\implies 5n^2+6n+7-n^2+4n=0
\\\\\\
4n^2+10n+7=0\\\\
-------------------------------\\\\
\begin{array}{llccll}
&{{ 4}}x^2&{{ +10}}x&{{ +7}}\\
&\uparrow &\uparrow &\uparrow \\
&a&b&c
\end{array}
\\\\\\
discriminant\implies b^2-4ac=
\begin{cases}
0&\textit{one solution}\\
positive&\textit{two solutions}\\
negative&\textit{no solution}
\end{cases}$

if you get a positive value, that means 2 real solutions
if you get 0, means 1 real solution only
if you get a negative value, is an imaginary root solution, same as saying no solution.

4 0

3 years ago

Describe the graph of the function.y = |x – 4| – 7

juin [17]

This is always ''interesting'' If you see an absolute value, you always need to deal with when it is zero:

(x-4)=0 ===> x=4,

so that now you have to plot 2 functions!

For x<= 4: what's inside the absolute value (x-4) is negative, right?, then let's make it +, by multiplying by -1:

|x-4| = -(x-4)=4-x
Then:

for x<=4, y = -x+4-7 = -x-3

for x=>4, (x-4) is positive, so no changes:

y= x-4-7 = x-11,

Now plot both lines. Pick up some x that are 4 or less, for y = -x-3, and some points that are 4 or greater, for y=x-11

In fact, only two points are necessary to draw a line, right? So if you want to go full speed, choose:

x=4 and x= 3 for y=-x-3

And just x=5 for y=x-11

The reason is that the absolute value is continuous, so x=4 works for both:

x=4===> y=-4-3 = -7

x==4 ====> y = 4-11=-7!

abs() usually have a cusp int he point where it is =0

Hope it helps, despite being this long!

3 0

3 years ago

Read 2 more answers

Penelope goes to work after school for 4.5 hours on Mondays, Tuesdays, and Fridays. She doesn’t have classes on Wednesdays or Th

iVinArrow [24]

Answer:

Her hourly rate is $14.

Step-by-step explanation:

Given:

Penelope goes to work after school for 4.5 hours on Mondays, Tuesdays, and Fridays.

She works 8 hours each on Wednesdays or Thursdays.

Now, to find her hourly rate.