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dybincka [34]
3 years ago
8

Help me please I could really use it!!!!

Mathematics
1 answer:
lyudmila [28]3 years ago
5 0
It is A because you subsitute the x in the equation A) (2x-8)(7x+5)=0 x=4 x=5,7 (fraction)
subtitute the x now and you get
(2(4)-8)(7(-5,7)+5) = 0
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Is the mean resistant
Dvinal [7]
Hold on just have to type before I can see the question
8 0
3 years ago
The sum of first three terms of a finite geometric series is -7/10 and their product is -1/125. [Hint: Use a/r, a, and ar to rep
Alchen [17]
Ooh, fun

geometric sequences can be represented as
a_n=a(r)^{n-1}
so the first 3 terms are
a_1=a
a_2=a(r)
a_2=a(r)^2

the sum is -7/10
\frac{-7}{10}=a+ar+ar^2
and their product is -1/125
\frac{-1}{125}=(a)(ar)(ar^2)=a^3r^3=(ar)^3

from the 2nd equation we can take the cube root of both sides to get
\frac{-1}{5}=ar
note that a=ar/r and ar²=(ar)r
so now rewrite 1st equation as
\frac{-7}{10}=\frac{ar}{r}+ar+(ar)r
subsituting -1/5 for ar
\frac{-7}{10}=\frac{\frac{-1}{5}}{r}+\frac{-1}{5}+(\frac{-1}{5})r
which simplifies to
\frac{-7}{10}=\frac{-1}{5r}+\frac{-1}{5}+\frac{-r}{5}
multiply both sides by 10r
-7r=-2-2r-2r²
add (2r²+2r+2) to both sides
2r²-5r+2=0
solve using quadratic formula
for ax^2+bx+c=0
x=\frac{-b \pm \sqrt{b^2-4ac}}{2a}
so
for 2r²-5r+2=0
a=2
b=-5
c=2

r=\frac{-(-5) \pm \sqrt{(-5)^2-4(2)(2)}}{2(2)}
r=\frac{5 \pm \sqrt{25-16}}{4}
r=\frac{5 \pm \sqrt{9}}{4}
r=\frac{5 \pm 3}{4}
so
r=\frac{5+3}{4}=\frac{8}{4}=2 or r=\frac{5-3}{4}=\frac{2}{4}=\frac{1}{2}

use them to solve for the value of a
\frac{-1}{5}=ar
\frac{-1}{5r}=a
try for r=2 and 1/2
a=\frac{-1}{10} or a=\frac{-2}{5}


test each
for a=-1/10 and r=2
a+ar+ar²=\frac{-1}{10}+\frac{-2}{10}+\frac{-4}{10}=\frac{-7}{10}
it works

for a=-2/5 and r=1/2
a+ar+ar²=\frac{-2}{5}+\frac{-1}{5}+\frac{-1}{10}=\frac{-7}{10}
it works


both have the same terms but one is simplified

the 3 numbers are \frac{-2}{5}, \frac{-1}{5}, and \frac{-1}{10}
6 0
3 years ago
A root of x2<br> – 5x – 1 = 0 is
My name is Ann [436]
x =(-5+√29)/2= 0.193
5 0
3 years ago
if A is the number of degrees and B is the number of grades of any angle ,prove that : B=A+A/9 [FULL PROCESS REQUIRED]​
Gre4nikov [31]
We know
90
∘
=
1
right angle
=
100
g
So
A
∘
=
(
100
90
⋅
A
)
g
Hence by the given condition
B
=
(
100
90
⋅
A
)
=
10
9
A
=
A
+
(
A
9
)
Answer

3 0
3 years ago
<img src="https://tex.z-dn.net/?f=%5Cfrac%7Br%7D%7B2%7D%2B%5Cfrac%7Bs%7D%7Br%7D%20-%5Cfrac%7Br%7D%7B4%7D%2B%5Cfrac%7B1%7D%7B5%7D
zloy xaker [14]

Answer:

-1/20

Step-by-step explanation:

r/2 + s/r - r/4 + 1/5 =

= -1/2 + 0/(-1) - (-1)/4 + 1/5

= -1/2 + 1/4 + 1/5

= -10/20 + 5/20 + 4/20

= -5/20 + 4/20

= -1/20

3 0
3 years ago
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