How do you combine #(x^2-bx-7) - (3x^2+2x-4)#?

2 Answers
Jul 22, 2015

Group by like powers of #x# and perform standard arithmetic to get:
#color(white)("XXXX")##-2x^2-(b+2)x -3#

Explanation:

#(x^2−bx−7)−(3x^2+2x−4)#
#color(white)("XXXX")#Regroup as:
#(x^2-3x^2) + (-bx -2x) + (-7 -(-4))#

#=-2x^2 -(b+2)x -3#

Jul 22, 2015

#(x^2-bx-7)-(3x^2+2x-4)=-2x^2-bx-2x-3#

Explanation:

#(x^2-bx-7)-(3x^2+2x-4)#

Distribute the negative sign to each of the terms inside the second set of parentheses, then remove the parentheses.

#x^2-bx-7-3x^2-2x+4#

Group like terms.

#x^2-3x^2-bx-2x-7+4#

Combine.

#-2x^2-bx-2x-3#