The expression x2+3x−28 can be written as (x+a)(x−b), and the expression x2−10x−56 written as (x+2b)(x+c), where a , b, and c are integers such that c>0. What is the value of 2c−a?
I wish I could help u guys but I forgot how to solve these type of questions cuz I used to solve them in grade 9 and 10
x2 + 3x - 28 = (x - 4)(x + 7) = ( x + (-4) )( x - (-7) ) = (x + a)(x - b)
x2 - 10x - 56 = (x - 14)(x + 4) = ( x + 2(-7) )( x + 4 ) = (x + 2b)(x + c)
So...
a = -4 , b = -7 , c = 4
And...
2c - a = 2(4) - -4 = 8 - -4 = 12
