A number is such that three times the product of the number and 4 exceeds its square by 20 .find the number

quadratic equation sum

x = the number

3(4x) = x² + 20 {created the equation based on the first sentence}
12x = x² + 20 {multiplied 3 by 4x}
x² - 12x + 20 = 0 {subtracted 12x from both sides}
(x - 10)x - 2) = 0 {factored into two binomials}
x - 10 = 0 or x - 2 = 0 {set each factor equal to 0}
x = 10 or x = 2 {added 10 and 2, respectively}

10 and 2 are the numbers

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3*4*n=n^2+20

n^2-12n+20 = 0

(n-10)(n-2) = 0

n = 10 or n = 2