Question 20:
#f(x)=x+9 \ \ \ \, g(x)=5x#
#f(3) + g(-3)#
This is just saying, plug in 3 for #f(x)# and plug in -3 for #g(x)# and add the result.
#f(3)=(3)+9=12#
#g(-3)=5(-3)=-15#
#f(3)+g(-3)=>12+(-15)=color(blue)(-3)#
This is the first choice.
Question 21:
#f(x)=3x-3 \ \ \ \, g(x)=2x#
#f(4)-g(2)#
This is just saying, plug in 4 for #f(x)# and plug in 2 for #g(x)# and subtract the result.
#f(4)=3(4)-3=9#
#g(2)=2(2)=4#
#f(4)-g(2)=>9-4=color(blue)(5)#
This is the first choice again.
Question 22:
#f(x)=2x^2+5color(white)(8888)# , #g(x)=2x#
This is asking us to multiply the two expressions:
#f(x)*g(x)=(2x^2+5)(2x)#
# \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ =(2x)(2x^2)+(2x)(5)#
# \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ =color(blue)(4x^3+10x)#
This is the fourth choice.
