How To Cross Multiply

Introduction of How to Cross Multiply:

Cross multiplication is the easiest method that can be done in the equation form of two fraction form. For Example: `(4)/(16)` = `(3)/(12)`. By using the cross multiply method, we can check this given example as 4 * 12 = 48 and 16 * 3 = 48. Now it be proved that  `(4)/(16)` = `(3)/(12)`. Let see how to do the cross multiply and example problem of cross multiply.


Rules – How to Cross Multiply:


Let take

`(P)/(Q)` ….. Fraction 1

`(R)/(S)` ………. Fraction 2

Now equate the two fractions as in the form of `(P)/(Q)` … = `(R)/(S)` ……fraction equation

Rule 1: How to cross multiply means, multiply denominator of the fraction 2 with numerator of the fraction 1 as well as multiply denominator of the fraction 1 with numerator of the fraction 2

P * S = Q * R

Rule 2: Multiply the term on both sides of the fraction equation, and then the value of the term remains unchanged.

PS = QR

Multiply term A on both sides then its value is not changed. PSA = QRA.

Let we see example problem of how to cross multiply.


Example Problem – How to Cross Multiply:


Example 1:

How to find the value of x in given equation `(3)/(x)` = `(4)/(8)`?

Solution:

Step 1: Multiply 8 with the numerator of the fraction `(3)/(x)`.

3 * 8 = 24

Step 2: Multiply the denominator of the fraction 3/x with numerator of the fraction 4/8.

x * 4 = 4 x

Step 3: Equate above two steps, 4 x = 24

Step 5: Divide 4 by both sides, we get 4 * (`(x)/(4)`) = `(24)/(4)`

Then the value of x = 6

Answer: x= 6

Example 2:

How to solve this equation `(X - 3)/(4)` = `(5)/(2)`?

Solution:

Step 1: Multiply 2 with the numerator of the fraction `(X - 3)/(4)`.

2 * (X - 3) = 2X - 6

Step 2: Multiply the denominator of the fraction `(X - 3)/(4)` with numerator of the fraction `(5)/(2)`.

4 * 5 = 20

Step 3: Equate above two steps, 2X – 6 = 20

2X = 14

Step 5: Divide 2 by both sides, we get 2 * (`(X )/(2)`) = `(14)/(2)`

Then the value of X = 7

Answer: x= 7