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Vlad [161]
3 years ago
5

How many solutions are there for the system x^2+4y^2=100 and 4y-x^2=-20

Mathematics
1 answer:
never [62]3 years ago
6 0
There are 5 solutions for this system.

x^2 + 4y^2 = 100  ____1
4y - x^2 = -20  ____2
Add both 1 & 2 together. x^2 gets cancelled
4y^2 + 4y = 80   (send 80 to the other side and divide by 4)
Then equation the becomes : y^2 + y -20 =0
Now factorise the equation: (y+5) (y-4) = 0
Solve for y :  y = -5 and y = 4
Using the values of y to find the values of x. From equation 1:
x^2 = 100 - 4y^2    x = /100 - 4y^2  (/ means square root) Replace values of y
y = -5, x = /100 - 4(-5)^2 = /100 - 100 = 0
y = 4, x = /100 - 4(4)^2 = / 100 - 64 = /36 = -6 or 6
Thus we have 6 solutions y = -5, 4 and x = -6, 0, 6
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A ladder is leaning up against a house. The ladder is 20 feet long and the base of the ladder is 12 feet away from the house. Ho
MrRa [10]

Answer:

16 feet

Step-by-step explanation:

The length of the ladder=20 feet

Distance from the base of the ladder to the house = 12 feet

You will notice that a wall is vertical and the ladder makes an angle with the horizontal ground(making it the hypotenuse). This is a right triangle problem.

To find the how far up the house can the ladder can reach, we simply find the third side of the right triangle.

From Pythagoras theorem

Hyp^2=Opp^2+Adj^2\\20^2=12^2+Adj^2\\Adj^2=400-144\\Adj^2=256\\Adj=\sqrt{256}=16

The third side of the right triangle is 16. Therefore the ladder leans 16 feet from the ground.

8 0
3 years ago
Read 2 more answers
Please help meeeeee with this
aleksandrvk [35]
Alright, let's do all of these (though this is a bit long).
1.
The constant is 1.8. All other values are coefficients to variables, which as the name implies will change.
2.
1 hour is 60 minutes, 1 minute is 60 seconds.
So, 4.2 *60 *60 = 15120 seconds.
3.
<span>−5x−4(x−6)=−3-5x-4(x-6)=-3
Let's move all x to one side, and all other numbers to another.
-5x-4(x-6)=-3-5x-4(x-6)=-3
x can be any value you want, if you actually solve this you'll only end up with -3 = -3, which is correct, of course.
Let me show you:
</span><span>−5x−4(x−6)=−3-5x-4(x-6)=-3
+5x +4(x-6)        +5x +4(x-6)
-3 = -3
The value of x is irrelevant, then. X can be any real number.
4.
I'm going to assume it was an error in printing with this? If not please correct me.
m=a+2b(or b2)
subtract 2b from each
a=m-2b
(This question seems kind of odd. We should probably address this in the comments.)
5.
</span><span>5(x−2)<−3x+6
Move all x to one side, numbers to other.
5x-10<-3x+6
+3x     +3x
    +10      +10
8x<16
/8
<span>x < 2
</span>6.
y-3=3(x-5)
alright, to find zeros set one variable to zero and solve
x first
-3=3x-15
+15    +15
3x=12
/3
x=4
x-int is (4,0)
now y
</span>y-3=3(0-5)
y-3=-15
+3     +3
y=-12
so y-int is (0,-12)
i've got to sleep now so i'll do the rest tomorrow. Sorry for the incomplete answer.

8 0
3 years ago
Slope of (3, 300)(5, 180) in y=mx+b form​
vredina [299]

Answer: ok so if you look at the difference it is 120 in 2 hours so to find 1 hour you divide it by 2, or split it in half and that means 60 and it is Decreasing so c is the answer. As for what y= it is y=-60x+480

60 cubic feet and you start out with 480

Step-by-step explanation:

120/2=60

decreasing

c

And y=-60x+480

6 0
3 years ago
What makes (a + 2)(b – 9) = 0 true?
prohojiy [21]
B would have to equal 9 and a should equal -2 to get 0
5 0
3 years ago
Read 2 more answers
There are 2125 seats in a stadium the stadium is divided into 25 sections how many seats are in each section
Fofino [41]
There are 85 seats in each section. 2125 divided by 25 is 85.
4 0
3 years ago
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