How do you expand: #(4x + 5)^2#?

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Answer 1 · 2017-11-14T01:18:19

See a solution process below;

The question is: What is #(4x + 5)^2#

We can use this rule for quadratics:

#(color(red)(x) + color(blue)(y))^2 = color(red)(x)^2 + 2color(red)(x)color(blue)(y) + color(blue)(y)^2 #

Let #x = 4x# and let #y = 5#

Substituting gives:

#(color(red)( 4xx) + color(blue)(5))^2 =>#

#color(red)(( 4x))^2 + (2 * color(red)( 4x) * color(blue)(5)) + color(blue)(5)^2 =>#

#16x^2 + 40x + 25#