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3 years ago

X2 + 4x - 21 = 0 quadratic formula

Mathematics

1 answer:

Elena-2011 [213]3 years ago

6 0

Answer:

Step-by-step explanation:

x2 +4x-21=0. solve for x

$x = \frac{7}{2}$

$x = 3 \frac{1}{2} \ x = 3.5$

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How does product (result) of (a-b)2 compare the product (a+b)

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I'm assuming you mean (a-b)^2 : (a+b)^2

a^2 + b^2 cancel out leaving

-2ab versus +2ab

Therefore (a+b)^2 is +4ab greater.

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2 years ago

Two numbers are between 20 and 30. their greatest common factor is 4.Which two numbers could they be?

Andrew [12]

24 and 28
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3 years ago

Solve the following system of equations graphically on the set of axes below.

ivann1987 [24]

Step-by-step explanation:

y=-1

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2 years ago

Sviatoslav solved the quadratic equation x^2-x-1=0 by completing the square. In the process, he came up with the equivalent equa

zimovet [89]

Answer:

$x=\frac{1+\sqrt5}{2}$ and $x=\frac{1-\sqrt5}{2}$

and b= $\frac{5}{4}$

Step-by-step explanation:

We are given that a quadratic equation

$x^2-x-1=0$

We have to solve the equation by completing square and find the value of b.

$(x)^2-2\times x\times \frac{1}{2}+(\frac{1}{2})^2-(\frac{1}{2})^2-1=0$

$(x-\frac{1}{2})^2-\frac{1}{4}-1=0$

$(x-\frac{1}{2})^2-\frac{1-4}{4}=0$

$(x-\frac{1}{2})-\frac{5}{4}=0$

$(x-\frac{1}{2})^2-(\frac{\sqrt5}{2})^2=0$

$(x-\frac{1}{2})^2=(\frac{\sqrt5}{2})^2$

$x-\frac{1}{2}=\frac{\sqrt5}{2}$ and $x-\frac{1}{2}=-\frac{\sqrt5}{2}$

$x=\frac{\sqrt5}{2}+\frac{1}{2}=\frac{1+\sqrt5}{2}$

And $x=\frac{1}{2}-\frac{\sqrt5}{2}=\frac{1-\sqrt5}{2}$

Therefore, $x=\frac{1+\sqrt5}{2}$ and $x=\frac{1-\sqrt5}{2}$

and b= $\frac{5}{4}$

6 0

2 years ago

One leg of a right triangle is 7 inches longer than the smaller leg and the hypotenuse is 8 inches longer than the smaller leg.

Makovka662 [10]

Smaller leg = x
longer leg = y
hypotenuse = z

y=x+7
z=x+8

due to
${z}^{2} = {x}^{2} + {y}^{2} \\ (x + 8) ^{2} = {x}^{2} + (x + 7) ^{2} \\ {x}^{2} + 16x + 64 = {x}^{2} + {x}^{2} + 14x + 49 \\ {x}^{2} + 16x + 64 = 2 {x}^{2} + 14x + 49 \\ {x}^{2} - 2 {x}^{2} + 16x - 14x + 64 - 49 = 0 \\ - {x}^{2} + 2x + 15 = 0 \\ {x}^{2} - 2x - 15 = 0 \: \: (multiplied \: by \: - 1) \\ (x - 5)(x + 3) = 0 \\ then \: \: x = 5 \: \: or \: \: x = - 3$
but x cannot be -3
so smaller leg is 5 inches

then longer leg = 5+7 = 12 inches
and hypotenuse = 5+8 = 13 inches

3 0

2 years ago