What is the Value of x?

‘X’ is used in algebra as a variable. It is often used for unknown values. 

‘X’ is sometimes called ‘unknown’.

Variables can be letters, numbers, symbols, or a combination of those. It does not have to be “X”. It can be either “Y” or “W”.

For example:


x =5-1

x =4

Here x is unknown and the value for x is 4.

How Do You Solve for x?

Solve the equation for x by putting the variable on one side and putting all the remaining values on the other side. Calculate the result by simplifying the values.

Let’s solve the equation as

 x + 5= 9

Subtract 2 from both sides

⇒ x + 5- 5 = 9 – 5

⇒ x = 4

Now, check the answer, x = 4 by back substitution in the equation. We get 4 + 5= 9.

L.H.S = R.H.S

To find an unknown angle in a triangle

Using properties of triangles or the Pythagorean theorem, we can solve for x  the unknown side or angle in a triangle.


solve for x in a triangle 

△ ABC is right-angled at B with two of its legs measuring 3 units and 4 units. Find the hypotenuse x.





Solve for Equations

We solve two equations for x,

[katex]x-4y=4 [/katex] [katex] eq(1)[/katex].

[katex]4x-y=16[/katex] [katex]eq(2)[/katex].

From eq(1)

Derive the value of x

[katex]x=4+4y[/katex] [katex]eq(3)[/katex].

Put it [katex]x=4+4y[/katex]. in eq(2)

[katex]4(4+4y)-y[/katex] =[katex]16[/katex].

[katex]16+16y-y[/katex] =[katex]16[/katex].

[katex]15y[/katex] = [katex]16-16[/katex].


Put [katex]y=0[/katex] [katex]eq(3)[/katex].




[katex][x,y] =[4,0][/katex].

Solve for x in Fractions

we simply do the cross multiplication and simplify the equation to find x.

[katex]\frac x{20}=\frac3{10}[/katex].

Multiply both sides with [katex]20[/katex].

[katex]\frac x{20}\times20=\frac3{10}\times20[/katex].



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