What is the standard form of #y= (x + 2)(x + 5)#?

2 Answers
Dec 1, 2015

#y=x^2+7x+10#

Explanation:

The "standard form" for a quadratic is (in general)
#color(white)("XXX")y=ax^2+bx+c#
with constants #a, b, and c#

Dec 1, 2015

#y=x^2+7x+10#
Look at the method. It is using something called the 'Distributive' law

Explanation:

Given #y= (color(green)(x)color(red)(+)color(blue)(2))(x+5)#

#y=color(green)(x)(x+5) color(red)(+)color(blue)(2)(x+5)#

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Notice that the sign of the #color(blue)( 2)# follows it.
If the sign had been negative then we would have #color(red)(-)color(blue)(2)(x+5)#
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
#y=(color(green)(x) xx x)+(color(green)(x) xx5)color(white)(....)+color(white)(....)(color(blue)(2) xx x)+(color(blue)(2)xx5)#

#y=x^2+5x+2x+10#

#y=x^2+7x+10#