For the equation 4(2x-3)-(mx+5)=5x+b to be an identity, which of the following must be true about the constants m and b? Show your work

(1) m = 3 and b = -7
(2) m = 8 and b = 17
(3) m = -3 and b = -15
(4) m = 3 and b = 17

Respuesta :

Given:

The equation is

[tex]4(2x-3)-(mx+5)=5x+b[/tex]

To find:

The values of m and b.

Solution:

We have,

[tex]4(2x-3)-(mx+5)=5x+b[/tex]

Using distributive property, we get

[tex]8x-12-mx-5=5x+b[/tex]

On combining like terms, we get

[tex](8-m)x+(-12-5)=5x+b[/tex]

[tex](8-m)x-17=5x+b[/tex]

On comparing both sides, we get

[tex](8-m)=5[/tex]

[tex]-m=5-8[/tex]

[tex]-m=-3[/tex]

[tex]m=3[/tex]

And,

[tex]b=-17[/tex]

Therefore, m = 3 and b = 17.

Note: All options are incorrect.