Question

whqt is the cross multiplication​

Answer 1

Answer:

Step-by-step explanation:

Cross Multiply

To cross multiply is to go

from this:  

812 =  23

to this:  

8 × 3 = 12 × 2

How Does it Work?

Multiplying the top and bottom of a fraction by the same amount doesn't change its value.

Step 1: Multiply the top and bottom of the first fraction by the bottom number of the second fraction.

8 × 312 × 3 =  23

Step 2: Multiply the top and bottom of the second fraction by the bottom number that the first fraction had.

8 × 312 × 3 =  2 × 123 × 12

And Magic! The bottom of both fractions is now 12 × 3

Step 3: We can get rid of the 12 × 3 (as we are dividing both sides by the same amount) and the equation is still true:

8 × 3 = 12 × 2

Job Done!

In practice, though, it is easier to skip the steps and go straight to the "cross-multiplied" form.

Using Variables

The general case, using variables instead of numbers, is:

To cross multiply is to go from this:  ab =  cd

To this: ad = bc

To remember think cross (x) multiply:

Cross multiplication can help speed up a solution. Like in this example:

Example: Find "x" in  x8 =  2x

Start with:   x8 =  2x

Cross multiply: x2 = 8 × 2

Calculate: x2 = 16

And solve: x = 4 or −4