Question

What is the discriminant of f(x) = -2x^2 +3x +5
@Aleah.wood1398

Answer 1

one second!

Answer 2

for a quadratic

\[ax^2 + bx + c\]

the discriminant is

\[\Delta = b^2 - 4ac\]

you have a = -2, b = 3 and c = 5

sibstitute and calculate

Answer 3

Discriminant=b^2-4(a)(c)=3^2-4(-2)(5)=49

Answer 4

A rectangle shed covers 800 square feet of ground. it is 10 ft longer than it is wide. What is the width of the shed to the nearest tenth of a foot?
@Aleah.wood1398

Answer 5

this is a tricky question

Answer 6

It really is

Answer 7

start by drawing a diagram



include the given information and get an equation for the area.

so what can you say about the area in terms of the width, w

Answer 8

the width is multiplied twice in the area?

Answer 9

that makes it alot easier^^

Answer 10

can you distribute

\[(w + 10) \times w = ?\]

and you will need the general quadratic formula for the solution

Answer 11

which is what?

Answer 12

@campbell_st

Answer 13

can you expand or distribute ?

Answer 14

distribute

Answer 15

it means to multiply the term outside by both terms inside the brackets

Answer 16

got it

Answer 17

Im still not sure how to solve it

Answer 18

so what did you get...?

Answer 19

do i do (800 +10) x800?

Answer 20

using the given area information you get

\[(w + 10) \times w = 800\]

you still have the same problem... you need to distribute

Answer 21

subtract 10 from both sides?

Answer 22

no....the process of expanding or distributing involves multiplying each term inside the brackets by the term outside the brackets

so what is

\[w \times w = ?~~~~ and ~~~~~ 10 \times w = ?\]

Answer 23

w^2 and 10 w

Answer 24

great...

so now

\[w^2 + 10w = 800\]

rewriting the equation

\[w^2 + 10w - 800 = 0\]

now solve for w... you'll need the general quadratic formula

Answer 25

what is the general formula?

Answer 26

well its

\[w = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}\]

for a quadratic

\[aw^2 + bw + c = 0\]

so match the information, substitute and then calculate an answer.

You only need the positive solution as measurements can't be negative

Answer 27

ill be using the quadratic right?

Answer 28

yes

Answer 29

i got aw^2 +10w-800=0

Answer 30

why aw^2... I gave you the equation... several posts ago its

\[w^2 + 10w - 800 = 0\]

so when you compare it to the general form

\[aw^2 + bw + c = 0\]

what are the values of a, b and c

Answer 31

i thought I ws to stay in the equation so its just w^2 +10w-800=0