The variables x and y are directly proportional, and y=4 when x=9. What is the value of y when x=18?

Mathematics

2 answers:

mezya [45]2 years ago

8 0

Answer:

The value of y is 20 when x = 15 <em> i think</em>

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Step-by-step explanation:

alexandr402 [8]2 years ago

5 0

Answer:

Step-by-step explanation:

Y=4 when x=9

X=18---> y=8

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Solve for x<br>6x²+2x-12

dem82 [27]

Answer:

Step-by-step explanation:

Solving for x means you have to factor. First factor out the GCF of 2 to get:

$2(3x^2+x-6)$ and now we'll factor using the regular old method of ac and then factoring by grouping. In our polynomial, a = 3, b = 1, c = -6. Therefore, a times c is 3 * -6 which is -18. We need some combinations of the factors of 18 that will add to give us 1, the b term in the middle. The factors of 18 are:

1, 18

2, 9

3, 6 and that's it. Hm...it seems that won't work, so let's throw this into the quadratic formula, going back to the original and a = 6, b = 2 and c = -12:

$x=\frac{-2+/-\sqrt{2^2-4(6)(-12)} }{2(6)}$ and

$x=\frac{-2+/-\sqrt{4+288} }{12}$ and

$x=\frac{-2+/-\sqrt{292} }{12}$ and

$x=\frac{-2+/-\sqrt{4*73} }{12}$ and

$x=\frac{-2+/-2\sqrt{73} }{12}$ which finally simplifies to

$x=\frac{-1+/-\sqrt{73} }{6}$ No wonder that didn't factor using the traditional method of factoring! We could have found that out by finding first the value of the discriminant, but oh well!