There is a proportional relationship between y and x. When x=2, y=-9.

Mathematics

1 answer:

suter [353]3 years ago

8 0

They just told me to answer a bunch of questions sorry i dont know this best of luck tho !

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what is the surface area of a rectangular prism that has a height of 5cm a width of 10cm and a depth of 4cm

Kamila [148]

2(5*10)+2(10*4)+2(5*4)=

2(50)+2(40)+2(20)=100+80+40=

220 cm^2

I found the answer by finding the areas of the 3 different sides, multiplying each area by 2 since each side has another side that is equal on a rectangular prism, then adding all of them together.

4 0

3 years ago

Please help!!

yarga [219]

Because this is a fourth degree that will be tricky to factor as it is, we will do a u substitution. Let $x^2=u$ . We can now rewrite that polynomial in terms of u: $u^2-7u-8=0$ . Filling into the quadratic formula we have $u=\frac{7+/-\sqrt{49-4(1)(-8)}}{2}$ . Simplifying down $u=\frac{7+/-\sqrt{81}}{2}$ and $u=\frac{7+9}{2}$ or $u=\frac{7-9}{2}$ . That means that u = 8 or u = -1. But don't forget that we let $u=x^2$ , so we have to put x-squared back in for u. That gives us $x^2=8$ which simplifies down to $+/-2\sqrt{2}$ . That also gives us $x^2=-1$ . When we take the square root of -1, we have to use the fact that -1 = i^2, so we sub that in to get $x=+/-i$ . All in all, your solutions are as follows: $2\sqrt{2},-2\sqrt{2},i,-i$ which is choice b.