How do you evaluate #-a ( a ^2 + 2a - 1)# for a = 2?

2 Answers
ProfLayton
Apr 22, 2016

-14

Explanation:

In substitution, we replace something for something else, in this case anytime we see #a#, we put a 2 there. Applying this:
#-2(2^2+2(2)-1)=-2(4+4-1)#
#=-2(7)#
#=-14#

Veddesh #phi#
Apr 22, 2016

#-14#

Explanation:

#color(blue)(-a(a^2+2a-1)# #"for"# #a=2#

Now substitute the value of #a# into the equation

#rarrunderbrace(-a)(underbrace(a^2)+2underbracea-1)#

#rarr-2(2^2+2(2)-1)#

#rarr-2(4+4-1)#

#rarr-2(7)#

#color(green)(rArr-14#

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