Solve 32x^2-285x+625=0

$$32 { x }^{ 2 } -285x+625 = 0$$

Solve for x

$$x=5$$

$$x = \frac{125}{32} = 3\frac{29}{32} = 3.90625$$

Steps Using the Quadratic Formula

All equations of the form ax^{2}+bx+c=0 can be solved using the quadratic formula: \frac{-b±\sqrt{b^{2}-4ac}}{2a}. The quadratic formula gives two solutions, one when ± is addition and one when it is subtraction.

$$32x^{2}-285x+625=0$$

This equation is in standard form: ax^{2}+bx+c=0. Substitute 32 for a, -285 for b, and 625 for c in the quadratic formula, \frac{-b±\sqrt{b^{2}-4ac}}{2a}.

$$x=\frac{-\left(-285\right)±\sqrt{\left(-285\right)^{2}-4\times 32\times 625}}{2\times 32}$$

Square -285.

$$x=\frac{-\left(-285\right)±\sqrt{81225-4\times 32\times 625}}{2\times 32}$$

Multiply -4 times 32.

$$x=\frac{-\left(-285\right)±\sqrt{81225-128\times 625}}{2\times 32}$$

Multiply -128 times 625.

$$x=\frac{-\left(-285\right)±\sqrt{81225-80000}}{2\times 32}$$

Add 81225 to -80000.

$$x=\frac{-\left(-285\right)±\sqrt{1225}}{2\times 32}$$

Take the square root of 1225.

$$x=\frac{-\left(-285\right)±35}{2\times 32}$$

The opposite of -285 is 285.

$$x=\frac{285±35}{2\times 32}$$

Multiply 2 times 32.

$$x=\frac{285±35}{64}$$

Now solve the equation x=\frac{285±35}{64} when ± is plus. Add 285 to 35.

$$x=\frac{320}{64}$$

Divide 320 by 64.

$$x=5$$

Now solve the equation x=\frac{285±35}{64} when ± is minus. Subtract 35 from 285.

$$x=\frac{250}{64}$$

Reduce the fraction \frac{250}{64} to lowest terms by extracting and canceling out 2.

$$x=\frac{125}{32}$$

The equation is now solved.

$$x=5 x=\frac{125}{32}$$

Steps for Completing the Square

Quadratic equations such as this one can be solved by completing the square. In order to complete the square, the equation must first be in the form x^{2}+bx=c.

$$32x^{2}-285x+625=0$$

Subtract 625 from both sides of the equation.

$$32x^{2}-285x+625-625=-625$$

Subtracting 625 from itself leaves 0.

$$32x^{2}-285x=-625$$

Divide both sides by 32.

$$\frac{32x^{2}-285x}{32}=-\frac{625}{32}$$

Dividing by 32 undoes the multiplication by 32.

$$x^{2}-\frac{285}{32}x=-\frac{625}{32}$$

Divide -\frac{285}{32}, the coefficient of the x term, by 2 to get -\frac{285}{64}. Then add the square of -\frac{285}{64} to both sides of the equation. This step makes the left hand side of the equation a perfect square.

$$x^{2}-\frac{285}{32}x+\left(-\frac{285}{64}\right)^{2}=-\frac{625}{32}+\left(-\frac{285}{64}\right)^{2}$$

Square -\frac{285}{64} by squaring both the numerator and the denominator of the fraction.

$$x^{2}-\frac{285}{32}x+\frac{81225}{4096}=-\frac{625}{32}+\frac{81225}{4096}$$

Add -\frac{625}{32} to \frac{81225}{4096} by finding a common denominator and adding the numerators. Then reduce the fraction to lowest terms if possible.

$$x^{2}-\frac{285}{32}x+\frac{81225}{4096}=\frac{1225}{4096}$$

Factor x^{2}-\frac{285}{32}x+\frac{81225}{4096}. In general, when x^{2}+bx+c is a perfect square, it can always be factored as \left(x+\frac{b}{2}\right)^{2}.

$$\left(x-\frac{285}{64}\right)^{2}=\frac{1225}{4096}$$

Take the square root of both sides of the equation.

$$\sqrt{\left(x-\frac{285}{64}\right)^{2}}=\sqrt{\frac{1225}{4096}}$$

Simplify.

$$x-\frac{285}{64}=\frac{35}{64} x-\frac{285}{64}=-\frac{35}{64}$$

Add \frac{285}{64} to both sides of the equation.

$$x=5 x=\frac{125}{32}$$