1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
xeze [42]
3 years ago
11

Solve by using substitution-4x+y=6   and   -5x-y=21  

Mathematics
2 answers:
spin [16.1K]3 years ago
4 0
\left \{ {{-4x+y=6} \atop {-5x-y=21}} \right. \\\\ \left \{ {{y=6+4x} \atop {-5x-y=21}} \right. \\\\Substitute\ first\ equation\ into\ the\ second\\\\
-5x-(6+4x)=21\\
-5x-6-4x=21\\
-9x-6=21\ \ \ |add\ 6\\\\
-9x=27\ \ \ |divide\ by\ -9\\\\
x=-3\\
y=6+4*(-3)=6-12=-6\\\\ \left \{ {{y=-6} \atop {x=-3}} \right.
NeX [460]3 years ago
3 0
So if you're solving by substitution, one equation must be in slope intercept form. Ill just go with the first one. 

-4x+y=6
<u>+4x        +4x
</u>y=6+4x

Now substitute the value of y in for the value of y in the second equation:
-5x-(6+4x)=21
-5x-6-4x=21
-9x-6=21
<u>     +6  +6
</u><u>-9x=27
</u>-9    -9

x=-3

Now input that into the first equation:
-4(-3)+y=6
12+y=6
<u>-12    -12</u>
y=-6


I HOPE THIS WAS HELPFUL! If it was, please rate my answer!

You might be interested in
Find the equation of a circle whose center is at (-3, 7) and radius is 9 units.
timurjin [86]

Answer:

(x + 3)² + (y - 7)² = 81

Step-by-step explanation:

the equation of a circle in standard form is

(x - h)² + (y - k)² = r²

where (h, k ) are the coordinates of the centre and r the radius

here (h, k ) = (- 3, 7 ) and r = 9 , then

(x - (- 3) )² + (y - 7)² = 9² , that is

(x + 3)² + (y - 7)² = 81

3 0
2 years ago
Read 2 more answers
Solve each equation? (n+2) ( n+1)= 0
Delicious77 [7]

Answer:

n=-2,\:n=-1

Step-by-step explanation:

\left(n+2\right)\left(n+1\right)=0\\\mathrm{Using\:the\:Zero\:Factor\:Principle:\quad \:If}\:ab=0\:\mathrm{then}\:a=0\:\mathrm{or}\:b=0\:\left(\mathrm{or\:both}\:a=0\:\mathrm{and}\:b=0\right)\\\mathrm{Solve\:}\:n+2=0:\quad n=-2\\n+2=0\\\mathrm{Subtract\:}2\mathrm{\:from\:both\:sides}\\n+2-2=0-2\\\mathrm{Simplify}\\n=-2\\\mathrm{Solve\:}\:n+1=0:\quad n=-1\\n+1=0\\\mathrm{Subtract\:}1\mathrm{\:from\:both\:sides}\\n+1-1=0-1\\Simplify\\n=-1\\\mathrm{The\:solutions\:to\:the\:quadratic\:equation\:are:}\\n=-2,\:n=-1

7 0
3 years ago
Read 2 more answers
What are the zeros of the function f(x) = x4 − 4x2 − 5?
Gekata [30.6K]

Answer:

A graph shows zeros to be ±3. Factoring those out leaves the quadratic

 (x-2)² +1

which has complex roots 2±i.

The function has roots -3, 3, 2-i, 2+i.

Step-by-step explanation:

4 0
2 years ago
Read 2 more answers
What is the square root of negative four
Dmitry [639]
The square root of negative four is 2
3 0
3 years ago
Find the area of the figure.( sides meet at right angles.)picture below
Tema [17]

You can divide the figure as follows:

  • A vertical rectangle, 5 meters tall and 2 meters wide, on the top right.
  • A horizontal rectangle, 2 meters tall and 5 meters wide, on the bottom left
  • A 2x2 meters square on the bottom right, where the two rectangles meet.

The area of the rectangles is 5x2=10 meters squared, while the area of the square is 2x2=4 meters squared.

So, the total area is 10+4=14 meters squared.

5 0
3 years ago
Other questions:
  • In a recent year 21.6% of all registered doctors were female if there were 54,100 female registered doctors that year what was t
    7·1 answer
  • Heyyyaaaa heyyyyy mathhhh
    10·1 answer
  • hiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiii i need help so ya pleasssseeeee oh and answer all of them
    5·1 answer
  • Item 4
    6·2 answers
  • Write 0.32 repeating as a fraction in simplest form.
    7·1 answer
  • Can I please get help on this?​
    8·1 answer
  • Ms. White drives 8 miles each way, to and from her office. If she does this 5 days each week for 10 weeks, how many total miles
    9·1 answer
  • Angle DEF and Angle FEG are complementary. mDef=(3x-4)°, and mDEG=(5x+6). Find x. ​
    14·2 answers
  • Please help quick ..
    15·1 answer
  • Help me pls
    5·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!