Answer
$$2x^{3}+6x^{2}+2x-4$$
Work Step by Step
$$(x^{2}+x-1)(2x+4)$$
1. Multiply the first term of each bracket together. $$(x^{2})(2x)=2x^{3}$$
2. Multiply the outermost terms of each bracket together.$$(x^{2})(4)= 4x^{2}$$
3. Multiply the middle term of the first bracket with the innermost term in the second bracket. $$(x)(2x)=2x^{2}$$
4. Multiply the middle term of the first bracket with the outermost term in the second bracket. $$(x)(4)=4x$$
5. Multiply the innermost terms of each bracket together. $$(-1)(2x)=-2x$$
6. Multiply the last terms of each bracket together. $$(-1)(4)=-4$$
7. Add all answers from steps 1-6 to get: $$2x^{3}+4x^{2}+2x+4x-2x-4$$
8. Collect like terms to get: $$2x^{3}+6x^{2}+2x-4$$
