Answer:
√
8
≈
3
Explanation:
Note that:
2
2
=
4
<
8
<
9
=
3
2
Hence the (positive) square root of
8
is somewhere between
2
and
3
. Since
8
is much closer to
9
=
3
2
than
4
=
2
2
, we can deduce that the closest integer to the square root is
3
.
We can use this proximity of the square root of
8
to
3
to derive an efficient method for finding approximations.
Consider a quadratic with zeros
3
+
√
8
and
3
−
√
8
:
(
x
−
3
−
√
8
)
(
x
−
3
+
√
8
)
=
(
x
−
3
)
2
−
8
=
x
2
−
6
x
+
1
From this quadratic, we can define a sequence of integers recursively as follows:
⎧
⎪
⎨
⎪
⎩
a
0
=
0
a
1
=
1
a
n
+
2
=
6
a
n
+
1
−
a
n
The first few terms are:
0
,
1
,
6
,
35
,
204
,
1189
,
6930
,
...
The ratio between successive terms will tend very quickly towards
3
+
√
8
.
So:
√
8
≈
6930
1189
−
3
=
3363
1189
≈
2.828427
Answer:
x = 5/6
Step-by-step explanation:
Cross multiply.
18(x - 2) = 3(-7)
Divide both sides by 3.
6(x - 2) = -7
Distribute the 6.
6x - 12 = -7
Add 12 to both sides.
6x = 5
Divide both sides by 6.
x = 5/6
Answer: x = 5/6
<span>3-2(Cosx)^2 - 3Sinx = 0.
Recall (Sinx)^2 + (Cosx)^2 = 1.
Therefore (Cosx)^2 = 1 - (Sinx)^2
Substitute this into the question above.
</span><span>3-2(Cosx)^2 - 3Sinx = 0
3 - 2(1 - (Sinx)^2) - 3Sinx = 0 Expand
3 - 2 + 2(Sinx)^2 - </span><span><span>3Sinx = 0</span>
1 + 2(</span><span>Sinx)^2 - 3Sinx = 0 Rearrange
2(Sinx)^2 </span><span><span>- 3Sinx + </span>1 = 0
Let p = Sinx
2p^2 - 3p + 1 = 0 Factorise the quadratic expression
2p^2 - p - 2p +1 = 0
p(2p -1) - 1(2p -1) = 0
(2p-1)(p -1) = 0
Therefore 2p-1=0 or (p-1) = 0
2p=0+1 or (p-1) = 0
2p=1 or p = 0 +1.
p=1/2 or p = 1 Recall p = Sinx
Therefore Sinx = 1/2 or 1.
For 0<u><</u>x<u><</u>360
Sinx =1/2, x = Sin inverse (1/2) , x = 30,
(180-30)- 2nd Quadrant = 150 deg
Sinx = 1, x = Sin inverse (1) , x = 90
Therefore x = 30,90 & 150 degrees.
Cheers.</span>
Is this simultaneous equations?
if yes then the first step is
make one of the unknown as the subject
