Shawna and her best friend Keisha go shopping. The function p(t) = 3x4 + 2x3 − 4x2 + 21 represents how much money each girl spent based on the number of hours they were shopping. If Shawna and Keisha each go shopping for 2 hours, how much money did they spend together?

Shawna and her best friend Keisha together spend $ 138Solution:Given that, Shawna and her best friend Keisha go shopping.The function given for money each girl spent based on the number of hours they were shopping is:[tex]p(t)=3 x^{4}+2 x^{3}-4 x^{2}+21[/tex]Find the amount of money that each girl spentFor t = 2 hours[tex]\begin{array}{l}{\mathrm{p}(2)=3(2)^{4}+2(2)^{3}-4(2)^{2}+21} \\\\ {\mathrm{p}(2)=3 \times 16+2 \times 8-4 \times 4+21} \\\\ {\mathrm{p}(2)=48+16-16+21} \\\\ {\mathrm{p}(2)=69}\end{array}[/tex]Find the amount of money that they spend togetherMultiply by 2 the amount of money that each girl spent[tex]2 \times 69 = 138[/tex]