# (x+5-2i)(x+5+2i) how do I work this out I can not remember please show me how to find the answer thanks!

embizze | High School Teacher | (Level 1) Educator Emeritus

Posted on

Expand `(x+5-2i)(x+5+2i)`

We use the extended distributive property:

`(x+5-2i)(x+5+2i)`

`=x^2+5x+2ix+5x+25+10i-2ix-10i-4i^2`

`=x^2+10x+25-4i^2` (but `i=sqrt(-1)=>i^2=-1` so)

`=x^2+10x+29`

Thus `(x+5-2i)(x+5+2i)=x^2+10x+29`
{"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0}