Question 397890
1. {{{7i^5-8i^4+5i^3-4i^2}}}

{{{7(i^2)(i^2)i - 8(i^2)(i^2)+ 5(i^2)i - 4i^2}}}........(i^2=-1)

{{{7(-1)(-1)i - 8(-1)(-1)+ 5(-1)i - 4(-1)}}}

{{{7i - 8 - 5i + 4}}}

{{{2i - 4  }}}



2. {{{6(i^2)(i^2) -(3i-7)- 8i^2 +(4 - 15i)}}}

 {{{6(-1)(-1) -(3i-7)- 8(-1) +(4 - 15i)}}}

{{{6 -3i + 7 + 8 + 4 -15i}}}

{{{25 -18i}}}



3. {{{(6i-7)(7i-6)}}}

{{{(6i(7i)-7*7i + 6i(-6) - 7(-6))}}}

{{{42(i)^2- 49i - 36i + 42}}}

{{{42(-1)- 85i + 42}}}

{{{-42 - 85i + 42}}}

{{{ - 85i }}}


4. {{{(8i-6)/2i}}}

{{{(8i/2i) -6/2i}}}

{{{(cross(8i)4/cross(2i)) -cross(6)3/cross(2)i}}}

{{{4 -(3/i)}}}


5. {{{(10-9i)/(5-3i)}}}........multiply nominator and denominator by {{{(5+3i)}}}

{{{((10-9i)(5+3i))/((5-3i)(5+3i))}}}


{{{((10*5+30i -45i+ 27(i)^2))/(5^2-(3i)^2)}}}


{{{((50 -15i+ 27(-1)))/(25 -(9(-1)))}}}


{{{(50 -15i - 27)/(25 +9)}}}


{{{(23 -15i )/34}}}