Question

If (3x - 4) (5x + 7) = 15x2 - ax -28, then a =​

Answer 1

Answer:

a=1

Step-by-step explanation:

15x^2+20x-21x-28=15x^2-ax-28

15^2-1x-28=15x^2-ax-28

on comparison

a=1

Answer 2

Answer:

a = -1

Step-by-step explanation:

$(3x - 4)(5x + 7) \\ 15 {x}^{2} + 21x - 20x - 28 \\ 15 {x}^{2} + 1x - 28 \\ 15 {x}^{2} - ax - 28 \\ - ax = 1x \\ - a = 1 \\ a = - 1$