How do you multiply $(-1 + 5a)^2$ ?

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Answer 1 · 2016-07-08T11:20:57

There are two ways: you use the special products rule, or you write out the square into $(-1+5a)(-1+5a)$

Special products:
$(A+B)^2=A^2+2AB+B^2$ where $A=-1 and B=5a$
$=(-1)^2+2*(-1)*5a+(5a)^2$
$=1-10a+25a^2$

Writing out the square and FOIL:
$=(-1)xx(-1)+(-1)xx(5a)+(5a)xx(-1)+(5a)xx(5a)$
$=1-5a-5a+25a^2$

How do you multiply (-1 + 5a)^2(-1 + 5a)^2?