Incorrect. The GCF of the three terms is $\displaystyle{5}{{x}}^{{2}}\usepackage{cmbright}\Huge\$ . So: $\displaystyle{5}{{x}}^{{4}}+{40}{{x}}^{{3}}-{100}{{x}}^{{2}}={5}{{x}}^{{2}}{\left({{x}}^{{2}}+{8}{x}-{20}\right)}\usepackage{cmbright}\Huge\$

You need to find two numbers whose product is $\displaystyle-{20}\usepackage{cmbright}\Huge\$ and whose sum is 8, in order to factor the trinomial into the product of two binomials. The correct answer is 2.