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3 years ago

Andrew is showing his work in simplifying −4.5 + 4.2 + 5.6 − 7.3. Identify any errors in his work or in his reasoning.

Mathematics

1 answer:

julia-pushkina [17]3 years ago

6 0

Answer:

D. Step 5

Step-by-step explanation:

Andrew made a mistake at last step.

<u>It should be:</u>

-11.8 + 9.8 = 9.8 - 11.8 = -2 but not -21.6

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3 years ago

In ΔBCD, the measure of ∠D=90°, the measure of ∠B=71°, and DB = 67 feet. Find the length of BC to the nearest tenth of a foot.

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3 years ago

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Use the quadratic formula to solve for the roots in the following equation. 4x 2 + 5x + 2 = 2x 2 + 7x – 1

Natali5045456 [20]

Answer:

So, The roots are $x= \frac{1+\sqrt{5}i}{2} \,\, and \,\,x= \frac{1-\sqrt{5}i}{2}$

Step-by-step explanation:

$4x^2 + 5x + 2 = 2x^2 + 7x - 1$

We need to solve the equation to find the roots using quadratic formula.

The quadratic formula is:

$x=\frac{-b\pm\sqrt{b^2-4ac}}{2a}$

Rearranging the above equation:

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$2x^2 -2x + 3 =0$

Where a =2 , b=-2 and c =3 Putting values in quadratic equation and solving:

$x=\frac{-b\pm\sqrt{b^2-4ac}}{2a}\\x=\frac{-(-2)\pm\sqrt{(-2)^2-4(2)(3)}}{2(2)}\\x=\frac{2\pm\sqrt{4-24}}{4}\\x=\frac{2\pm\sqrt{-20}}{4}\\\sqrt{-20} \,\,can\,\,be\,\, written\,\, as\,\, 2\sqrt{-5}\\ x=\frac{2\pm2\sqrt{-5}}{4}\\x=\frac{2+2\sqrt{-5}}{4} \,\, and \,\, x=\frac{2-2\sqrt{-5}}{4}\\x=\frac{2(1+\sqrt{-5})}{4} \,\, and \,\, x=\frac{2(1-\sqrt{-5})}{4}\\ x=\frac{1+\sqrt{-5}}{2} \,\, and \,\, x=\frac{1-\sqrt{-5}}{2}\\As \,\,we\,\, know\,\, \sqrt{-1} = i \\$

$x= \frac{1+\sqrt{5}i}{2} \,\, and \,\,x= \frac{1-\sqrt{5}i}{2}$

So, The roots are $x= \frac{1+\sqrt{5}i}{2} \,\, and \,\,x= \frac{1-\sqrt{5}i}{2}$

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