Question

62. Спростіть вираз: 1) (x + 2) (x - 9)- 3x (3 - 2x); 2) (a + 5) (a - 2) + (a + 4) (a - 5); 3) (y - 8) (2y + 1) - (3y + 1) (y - 6); 4) (2x - 3y) (2x + 3y) + (3x + 2y) (3x - 2y); 5) (x + 1)² - (x − 3) (x + 3); 6) (y - 4) (y + 3) - (y - 6)².​

Answer 1

$1) \\(x + 2) (x - 9)- 3x (3 - 2x)=x^2-9x+2x-18-9x+6x^2=7x^2-16x-18\\\\2) \\(a + 5) (a - 2) + (a + 4) (a - 5)=a^2-2a+5a-10+a^2-5a+4a-20=2a^2+2a-30\\\\3) \\(y - 8) (2y + 1) - (3y + 1) (y - 6)=2y^2+y-16y-8-3y^2+18y-y+6=-y^2+2y-2\\\\4) \\(2x - 3y) (2x + 3y) + (3x + 2y) (3x - 2y)=4x^2-9y^2+9x^2-4y^2=13x^2-13y^2\\\\5) \\(x + 1)^2 - (x - 3) (x + 3)=x^2+2x+1-x^2+9=2x+10\\\\6) \\(y - 4) (y + 3) - (y - 6)^2=y^2+3y-4y-12-y^2+12y-36=11y-48$