Algebra: A Combined Approach (4th Edition)

$(7x-2)(3x-1)$
$21x^{2}−13x+2$ First, identify two numbers that multiply with each other to become 42, the product of the constant and coefficient of x2 (21 × 2) and add together to become -13, the coefficient of x. From inspection, we identify these numbers as -6 and -7. Secondly split the coefficient of x into the sum of the two above numbers. $21x^{2}−13x+2$ $=21x^{2}+(-6-7)x+2$ $=21x^{2}-6x-7x+2$ Factorize by grouping to find the answer. $21x^{2}-6x-7x+2$ $=3x(7x-2)-(7x-2)$ $=(7x-2)(3x-1)$