Step 1. Gather like terms
[tex]7-(-5x*x)-10,4x
[/tex]
Step 2. Use Product Rule: [tex] x^{a} x^{b} = x^{a+b} [/tex]
[tex]7-(5 x^{2} )-10,4x[/tex]
Step 3. Simplify brackets
[tex]7+5 x^{2} -10,4x[/tex]
Step 4. Simplify [tex]7+5 x^{2} -10[/tex] to [tex] 5x^{2} -3[/tex]
[tex]5 x^{2} -3,4x[/tex]
7+5{x}^{2}-10