Question

how to factor 15x-7x-2

Answer 1

Use the butterfly method: you need to find two numbers that add up to a times c = 15 times -2 = -30, and the same two numbers need to add up to -7.

These two numbers are -10 and 3.
(-10)(3) = 30 and -10 + 3 = -7

Factored form: ( x - 10 )( x + 3 )