We need to solve the quadratic equation $2x(8 - 7x) = -11$ for $x$, and round the answers to 2 decimal places.

AlgebraQuadratic EquationsQuadratic FormulaReal NumbersApproximation
2025/5/7

1. Problem Description

We need to solve the quadratic equation 2x(87x)=112x(8 - 7x) = -11 for xx, and round the answers to 2 decimal places.

2. Solution Steps

First, expand the expression on the left side of the equation:
2x(87x)=16x14x22x(8 - 7x) = 16x - 14x^2.
Now the equation is 16x14x2=1116x - 14x^2 = -11.
Rearrange the equation to the standard quadratic form ax2+bx+c=0ax^2 + bx + c = 0:
14x2+16x+11=0-14x^2 + 16x + 11 = 0.
Multiply by 1-1 to make the leading coefficient positive:
14x216x11=014x^2 - 16x - 11 = 0.
Now, we use the quadratic formula to solve for xx:
x=b±b24ac2ax = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}
In this case, a=14a = 14, b=16b = -16, and c=11c = -11.
Plugging these values into the quadratic formula:
x=(16)±(16)24(14)(11)2(14)x = \frac{-(-16) \pm \sqrt{(-16)^2 - 4(14)(-11)}}{2(14)}
x=16±256+61628x = \frac{16 \pm \sqrt{256 + 616}}{28}
x=16±87228x = \frac{16 \pm \sqrt{872}}{28}
x=16±221828x = \frac{16 \pm 2\sqrt{218}}{28}
x=8±21814x = \frac{8 \pm \sqrt{218}}{14}
Now we find the two possible values of xx:
x1=8+218148+14.761422.76141.62571.63x_1 = \frac{8 + \sqrt{218}}{14} \approx \frac{8 + 14.76}{14} \approx \frac{22.76}{14} \approx 1.6257 \approx 1.63 (to 2 decimal places)
x2=821814814.76146.76140.48290.48x_2 = \frac{8 - \sqrt{218}}{14} \approx \frac{8 - 14.76}{14} \approx \frac{-6.76}{14} \approx -0.4829 \approx -0.48 (to 2 decimal places)

3. Final Answer

x=1.63,0.48x = 1.63, -0.48

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