x2 - 18x + 72 = 0
(x - 6)(x - 12) = 0
x ∈ {6, 12}
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x2 - 21x = 72x2 - 21x - 72 = 0(x - 24) (x + 3) = 0x = 24x = -3
As an equation if: 6x = 72 then x = 12
2x2 + 6x - 8 = 72 ∴ 2x2 + 6x + 64 =0 ∴ x2 + 3x + 32 = 0 This can not be factored, as x is not equal to any integer. Using the quadratic equation, we find that: x = -3/2 ± √119 / 2i
I assume you mean; X^2 - 72X - 735 = 0 The only way I would do this is by the quadratic formula discriminant (-72)^2 - 4(1)(-735) = 8124 and means two real roots X = - b (+/-) sqrt(b^2-4ac)/2a a = 1 b = - 72 c = - 735 X = - (-72) (+/-) sqrt[(-72)^2 - 4(1)(-735)]/2(1) X = 72 (+/-) sqrt(8124)/2 X = [72 (+/-) 2sqrt(2031)]/2 Ugly, but true.
Solving quadratic equations by the new Transforming Method. It proceeds through 3 Steps. STEP 1. Transform the equation type ax^2 + bx + c = 0 (1) into the simplified type x^2 + bx + a*c = 0 (2), with a = 1, and with C = a*c. STEP 2. Solve the transformed equation (2) by the Diagonal Sum Method that immediately obtains the 2 real roots y1, and y2. STEP 3. Divide both y1, and y2 by the coefficient a to get the 2 real roots of the original equation (1): x1 = y1 /a, and x2 = y2/a. Example 1. Solve: 12x^2 + 5x - 72 = 0 (1). Solve the transformed equation: x^2 + 5x - 864 = 0. Roots have different signs (Rule of Signs). Compose factor pairs of a*c = -864 with all first numbers being negative. Start composing from the middle of the factor chain to save time. Proceeding:.....(-18, 48)(-24, 36)(-32, 27). This last sum is -32 + 27 = -5 = -b. Then, the 2 real roots of (2) are: y1 = -32, and y2 = 27. Back to the original equation (1), the 2 real roots are: x1 = y1/a = -32/12 = -8/3, and x2 = y2/a = 27/12 = 9/4. Example 2. Solve 24x^2 + 59x + 36 = 0 (1). Solve the transformed equation x^2 + 59x + 864 = 0 (2). Both roots are negative. Compose factor pairs of a*c = 864 with all negative numbers. To save time, start composing from the middle of the factor chain. Proceeding:....(-18, -48)(-24, -36)(-32, -27). This last sum is -59 = -b. Then 2 real roots of equation (2) are: y1 = -32 and y2 = -27. Back to the original equation (1), the 2 real roots are: x1 = y1/24 = -32/24 = -4/3, and x2 = y2/24 = -27/24 = -9/8. To know how does this new method work, please read the article titled: "Solving quadratic equations by the new Transforming Method" in related links.