Solve using the method of your choice: (3x+10)(x+2)=3(x+5)+15 ?

1 Answer
Space Cat
Nov 16, 2017
  1. Expand both sides
  2. Simplify like terms
  3. Move all terms to one side and use the null factor law to solve for #x#

Explanation:

Expanding brackets
#3x^2 + 6x +10x+20=3x+15+15#

Simplifying like terms
#3x^2+16x+20=3x+30#

Moving terms to left hand side
#3x^2 +16x +20 -3x -30 =0#
#3x^2 +13x -10=0#

Split the middle term to factorise
#3x^2 +15x-2x-10=0#
#3x(x+5)-2(x+5)=0#
#(3x-2)(x+5)=0#

Therefore
#x=2/3 or -5#

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