(x+2)(x-2)= x²-4
(3a-5b)(5b+3a)= 9a²-25b²
(3a+b)²= 9a²+6ab+b²
(3x²-5y)²=9x⁴-30x²y+25y²
(x-3)²-x²= (x-3-x)(x-3+x)= -3*(2x-3)
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y = 13x² + 4x - 3
F = 13x³/3 + 4x²/2 - 3x = 13x³/3 + 2x² - 3x