08 Jan 2014

## Video 00070 Use array formula to solve an algebra equation

### Here is an Algebra equation:  9x – 7 = 47

If we know the value of x we can easily determine if the left side = the right side.

But in this case x is not a single value but rather a Domain (a set of numbers).  x can be 5, 6, 7 or 8.  We have four chances to get a true answer.

Here is the Excel formula —>  {=OR(9*{5,6,7,8}-7=47)}

### Here is what happens inside the formula:

Step 1:  Multiply the 9 with each number inside of the array constant:  {=OR({45,54,63,72}-7=47)}

Step 2:  Subtract 7 from each of the numbers inside of the array constant: {=OR({38,47,56,65}=47)}

Step 3:  Compare each number with 47 (TRUE means it’s the same):  {=OR({FALSE,TRUE,FALSE,FALSE})}

Step 4:  The final answer gives us TRUE (The OR function just needs 1 TRUE)

Download here or via my OneDrive (file 00070)

### Watch my YouTube video

See how I caught the issue and several ways to fix it.

### What are the ingredients to my solution?

OR function, constant array (that contains the 5,6,7,8), entered as an array formula that requires Control Shift Enter (not just enter).