Math 1 · Lesson 3 · Step One · part 7 of 9
The invisible 1s
Because 1 is the do-nothing number for multiplying, math lets it hide.
The invisible 1s
Because 1 is the do-nothing number for multiplying, math lets it hide. Writing it in is the second half of Step One.
Invisible coefficient
x means 1x. So x + 2x = 1x + 2x = 3x. And 5x − x = 5x + (−1x) = 4x, not 5. The lonely x was really 1x all along.
Invisible exponent
x means x¹. So x · x² = x¹ · x² = x³ (add the exponents, 1 + 2), not x². And −x is really (−1)x¹.
Why write them in early? The 1s never trip you on easy problems. They get you mid-problem, when your brain is busy. So reveal them at Step One, before the heavy lifting.