Question #d4f12

1 Answer
Nov 14, 2017

#49/4#

Explanation:

To make a complete square, we can make a square of #(ax+b)^2#.

#(ax+b)^2#
#=a^2x^2+2abx+b^2#

In #x^2-7x#,
#a^2=1 and 2ab=-7#
Therefore #a=1, b=-7/2# or #a=-1, b=7/2#

Hence, the required value
#=b^2#
#=(-7/2)^2 or (7/2)^2#
#=49/4#