Question 204642
Number 1.
{{{(x + 5)*(2x - 1) = 2x^2 - x + 10x - 5 = 2x^2 + 9x - 5}}}


Number 2.
{{{3*(x - 4)*(x + 3) - 2*(4x - 1)*(x + 1)}}}
{{{3*(x^2 + 3x - 4x - 12) - 2*(4x^2 + 4x - x - 1)}}}
{{{3*(x^2 - x - 12) - 2*(4x^2 + 3x - 1)}}}
{{{3x^2 - 3x - 36 - 8x^2 - 6x + 2}}}
{{{-5x^2 - 9x - 34}}}


Number 3a.
area = (7x - 2)*(x - 10)
={{{7x^2 - 70x - 2x + 20 = 7x^2 - 72x + 20}}}


Number 3b.
area = {{{7*70^2 - 72*70 + 20 = 34300 - 5040 + 20}}}
= 29280 square centimeters