Answer:
[tex]21x^{2}[/tex]
Step-by-step explanation:
[tex]4x^{2} +15x^{2} --2x^{2}[/tex]
[tex]4x^{2} +15x^{2} +2x^{2}[/tex]...........2 negatives signs next to each make a positive
[tex]21x^{2}[/tex].................................combine like terms
