Substitute $\displaystyle-{4}\usepackage{cmbright}\Huge\$ for x: $\displaystyle-{5}{{x}}^{{4}}=-{5}{{\left(-{4}\right)}}^{{4}}\usepackage{cmbright}\Huge\$ . You must use the correct order of operations. Apply exponents before multiplying. Remember that a negative number raised to the fourth power equals a positive number, and that a negative times a positive is a negative. The correct answer is $\displaystyle-{1},{280}\usepackage{cmbright}\Huge\$ .