How do you solve #a^2+11a=-18#?

1 Answer
Jan 19, 2017

Answer:

#a=-2, or -9#

Explanation:

#a^2+11a=-18#, add #18# to both sides,

#a^2+11a+18=-18+18#

#a^2+11a+18=0#, and now we try to factorize this expression,

#(a+2)(a+9)=0#,

you just have to practise playing around with these expressions to do this. We knew that the product of the real numbers must be #18#, and that the sum of their product with #a# must be #11a#. The factors #2# and #9# fulfills these criteria.