Question

Which equation is a quadratic equation?

y + 3 = 5x + 10

y + 4x2 = (4x − 2)(x + 3)

y − 8x = (x2 + 1)(9x − 7)

y = 2x + 7x(x + 1)

Answer 1

Quadratic equation is something that goes y = ax^2 + bx + c. A, B, and C can be any real number.

A is wrong because it's a linear equation, y = 5x + 7.
B is wrong because the 4x^2 is cancelled out, resulting in y = 10x - 6.
C. is wrong because it begins with 9x^3, that doesn't follow the pattern mentioned up top.
D. is right because its the last one left. Also, it simplifies to y = 7x^2 + 9x + 0, which follows that pattern.

Answer 2

tyvm for the answer i have more questions to ask i'll post on here or in the question thing so you can get more ratings if you want

Answer 3

No problem, I'm just avoiding my Math 141 HW by solving all these.

Answer 4

A firecracker shoots up from a hill 150 feet high with an initial speed of 110 feet per second. Using the formula H(t) = −16t2 + vt + s, approximately how long will it take the firecracker to hit the ground?

Answer 5

i can repost in the question thing if you want me to

Answer 6

This is fine, i'll make this my last one so I can finish on time. Have you guys taken calculus 1 yet?

Answer 7

not yet

Answer 8

Turns out you don't need it anyway. Using the numbers from the problem, v = 110, and the initial height, s = 150.

Equation becomes: H(t) = -16t^2 + 110t + 150. Since H(t) is height at time t, just plug 0, or the ground, where H(t) is, and solve for t.

0 = -16t^2 + 110t + 150

Solve using the quadratic forumula, or if you can factor it out, whichever is quicker (most likely the former if you have a calculator) and you'll get two answers, one negative, and one positive. Since the rocket isn't time traveling, it can't be in the past, and so the only possible answer is the positive one.

Answer 9

Here we go, used the quadratic formula calculator online, the answer is 8.040912457080074

Just make sure you know the quadratic formula for the test.

Answer 10

ik how to do it just im in a hury to get this test done

Answer 11

See above post for answer, t = 8.040912457080074