How to do this? Please help

Step-by-step explanation:
This equations are quadratic equations, which is on standard form,
[tex] {ax}^{2} + bx + c[/tex]
where a is the leading coefficient, b is the second coefficient, and c is the constant.
Both a and b are in quadratic equation so we need to find the constant separately.
Both sides are equal to zero so we can just subtract the terms not containing a or b in them to the opposite side.
[tex] {x}^{2} - 4 x + a = 0[/tex]
[tex] {x}^{2} + a = 4x[/tex]
[tex]a = - {x}^{2} + 4x[/tex]
For b,
[tex]2 {x}^{2} - 6x + b + 7 = 0[/tex]
[tex] - 6x + b + 7 = - 2 {x}^{2} [/tex]
[tex]b + 7 = - 2 {x}^{2} + 6x[/tex]
[tex]b = - 2 {x}^{2} + 6x - 7[/tex]