Answer
26x$^4$+9x$^2$+6x
Work Step by Step
Distribute the negative sign to the parentheses and then combine like terms.
(7x$^4$+4x$^2$+5x)-(-19x$^4$-5x$^2$-x)
7x$^4$+4x$^2$+5x+19x$^4$+5x$^2$+x
(7x$^4$+19x$^4$)+(4x$^2$+5x$^2$)+(5x+x)
26x$^4$+9x$^2$+6