2 x + 1 − 2 x − 1 2 x − 1 + 2 x + 1 = 3 5 , x = ?
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Great solution! Componendo does make it easier to manipulate such expressions.
Exactly the same way man!!!
I used an almost similar method
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Which one?
How did you then do it?
What I did is : 3√(2x-1)+3√(2x+1)=5√(2x+1)-5√(2x-1) then Then 8√(2x-1)=2√(2x+1) Then 4√(2x-1)=√(2x+1) Then (4√(2x-1))^2=(√(2x+1))^2 Then 16(2x-1)=2x+1 Then 32x-1=2x+1 Then 30x=17 Then x=17/30
Even though the answer is right but the way complety wrong. For instance 2/4=1/2 ,but that absolutely does not mean that 4=2. So if a/b=c/d then (a) will not necessarily equal (c) ,and (b)will not necessarily equal (d).
Cross multiplying works too.
⇒
2
x
+
1
−
2
x
−
1
2
x
−
1
+
2
x
+
1
=
3
5
Let
2
x
+
1
=
a
and
2
x
−
1
=
b
.
a
−
b
b
+
a
=
3
5
Multiplying by
(
a
+
b
)
on numerator and denominator.
a
−
b
b
+
a
×
a
+
b
a
+
b
=
3
5
a
2
−
b
2
a
2
+
b
2
+
2
a
b
=
3
5
1
2
x
+
4
x
2
−
1
=
3
5
Now cross multiplying.
6
x
+
3
4
x
2
−
1
=
5
6
x
−
5
=
−
3
4
x
2
−
1
Squring both sides.
3
6
x
2
+
2
5
−
6
0
x
=
3
6
x
2
−
9
−
6
0
x
=
−
3
4
x
=
3
0
1
7
yes this is exactly how i did it
Componendo and Dividendo is a lot better.
This is my way too :)
the same way i did
Let 2 x − 1 = A Let 2 x + 1 = B
B − A A + B = 3 5 3 A + 3 B = 5 B − 5 A 8 A = 2 B 4 A = B ( 4 A ) 2 = ( B ) 2 3 2 x − 1 6 = 2 x + 1 3 0 x = 1 7 x = 3 0 1 7
Hmmm... All the previous solutions look more complicated (I have no idea what Componento and Dividendo is lol). Here is my solution: ⇒ b − a a + b = 3 5 ⇒ 5 b − 5 a = 3 a + 3 b ⇒ 2 b = 8 a ⇒ b = 4 a ⇒ 2 x + 1 = 4 2 x − 1 Square both sides to yield: ⇒ 2 x + 1 = 3 2 x − 1 6 And so ⇒ 1 7 = 3 0 x ⇒ x = 3 0 1 7
I think that we must follow the method of componendo and dividendo because this was the way it was supposed to be done ( since, the problem maker strategically gave 5/3). Also, componendo and dividendo is very helpful sometimes, and can significantly simply the solution if done using algrbra....
It states that if- A/B=C/D, then, A+B/A-B=C+D/C-D
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⇒ 2 x + 1 − 2 x − 1 2 x − 1 + 2 x + 1 = 3 5 Applying Componento and Dividendo , ⇒ ( 2 x − 1 + 2 x + 1 ) − ( 2 x + 1 − 2 x − 1 ) ( 2 x − 1 + 2 x + 1 ) + ( 2 x + 1 − 2 x − 1 ) = 5 − 3 5 + 3 This simplifies to
⇒ 2 x − 1 2 x + 1 = 4 Squaring both sides and cross multiplying the terms, ⇒ 2 x + 1 + 1 6 ( 2 x − 1 ) ⇒ x = 3 0 1 7