<span>8x^2 -50
= 2(4</span><span>x^2 - 25)
= 2(2x + 5)(2x - 5)
hope it helps </span>
If you put brackets around (2+1), your method of working is:
1) 15-4*(2+1)=3
2) 15-4*3=3
3) 15-12=3
You don't need any more brackets, as the BIDMAS (brackets, Indices, division, multiplication, addition, subtraction) rule does the rest of the job for you.
The answer is therefore: 15-4*(2+1)=3
