How do you factor 16r^2 - 25a^2 16r225a2?

2 Answers
Apr 25, 2018

16r^2-25a^2=color(blue)((4r+5a)(4r-5a))16r225a2=(4r+5a)(4r5a)

Explanation:

Remember: (x^2-y^2)(x2y2) can be factored as (x+y)(x-y)(x+y)(xy)

Using 16r^216r2 as x^2x2 (that is using 4r4r as xx), and
using 25a^225a2 as y^2y2 (that is using 5a5a as yy)

we get
color(white)("XXX")(4r+5a)(4r-5a)XXX(4r+5a)(4r5a)

Apr 25, 2018

(4r-5a)(4r+5a)(4r5a)(4r+5a)

Explanation:

16r^2-25a^2" is a "color(blue)"difference of squares"16r225a2 is a difference of squares

"which factors in general as"which factors in general as

•color(white)(x)a^2-b^2=(a-b)(a+b)xa2b2=(ab)(a+b)

"here "16r^2=(4r)^2" and "25a^2=(5a)^2here 16r2=(4r)2 and 25a2=(5a)2

rArra=4r" and "b=5aa=4r and b=5a

rArr16r^2-25a^2=(4r-5a)(4r+5a)16r225a2=(4r5a)(4r+5a)