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2 years ago

What two numbers add to 9 and multiply to -70

1 answer:

4 0

X, y - the numbers

The numbers add to 9 and multiply to -70.
$x+y=9 \\
xy=-70 \\ \\
y=9-x \\
xy=-70 \\ \\
\hbox{substitute 9-x for y in the second equation:} \\
x(9-x)=-70 \\
9x-x^2=-70 \\
-x^2+9x+70=0 \\
-x^2+14x-5x+70=0 \\
-x(x-14)-5(x-14)=0 \\
(-x-5)(x-14)=0 \\
-x-5=0 \ \lor \ x-14=0 \\
x=-5 \ \lor \ x=14 \\ \\
y=9-x \\
y=9-(-5) \ \lor \ y=9-14 \\
y=14 \ \lor \ y=-5 \\ \\
(x,y)=(-5,14) \hbox{ or } (x,y)=(14,-5)$

The numbers are -5 and 14.

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3 years ago

Would you solve the equation 0.25x + 7 = 1/3x – 8 using fractions or decimals? Explain please.

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Answer:

$x = 180$

Step-by-step explanation:

Solve the value of $x$ :

$0.25x + 7 = \frac{1}{3}x - 8$

-Combine $\frac{1}{3}x$ and $0.25x$ by subtracting $0.25x$ by $\frac{1}{3}x$ :

$0.25x - \frac{1}{3}x + 7 = \frac{1}{3}x - \frac{1}{3}x - 8$

$-\frac{1}{12}x + 7 = -8$

-Subtract $7$ on both sides:

$-\frac{1}{12}x + 7 - 7 = -8 - 7$

$-\frac{1}{12}x = -15$

-Multiply both sides by $-12$ , the reciprocal of $-\frac{1}{12}$ :

$\frac{-\frac{1}{12}x}{-\frac{1}{12}} = \frac{-15}{-\frac{1}{12}}$

$x = -15 (-12)$

$x = 180$

Therefore, the value of $x$ is $180$ .

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3 years ago

Solve for s. 8 - 48 = 8 + 13

PtichkaEL [24]

Which number carry’s the s?

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3 years ago

How to substitute x=-2 and x=5 into 2x^2+6-20=0 to check my work

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First answer (x=-2)
...
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Second answer (x=5)
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(2)[(-5)^2]+6-20
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3 years ago

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