Question

What is the value of the expression when a = 5 and b = 3?

4a^2 - 5b^2

Answer 1

Substitute a=5 and b=3 into your equation like so:
4*(5)^2 - 5*(3)^2 = 4*25 - 5*9 = 100-45 = 55

Answer 2

oh , i figured because at first i was doing 4 x a then i was getting an wrong answer , THANKS !

Answer 3

yeah its a little tricky because you have to square it, its easy to just rewrite the letter as an empty bracket with the squared symbol, then put your number in to avoid accidentally not squaring :)

Answer 4

yea , ah thanks tho

Answer 5

can u help me with this one | What is the value of the expression 3 ^–4?

Answer 6

when you see a negative sign in the index (the power) it means you have to invert the expression. So the expression becomes 1/(3^4), because when you invert the negative disappears. Simplifying this it now becomes 1/81, which is approx. 0.0123456789...

Answer 7

that is actually a really awesome number haha

Answer 8

*also by invert i mean take the reciprocal

Answer 9

yea i got that lmao yea it is awesome number

Answer 10

the answer choices is | -81 | -12 | -1/81 | 1/81 tho

Answer 11

choose 1/81

Answer 12

the negatives are there to trick you

Answer 13

a negative index does not make a negative number

Answer 14

yea i figured , i just got 1/81 to haha stupid negatives

Answer 15

:)

Answer 16

are you actually an substitute because them are kinda like teacher answers and teacher help

Answer 17

nah im just a high level maths student haha

Answer 18

ok i got this question 1/4^-3 and i got .015625 out of 4^-3 and divide it with 1 and got 64 . is that right ?

Answer 19

yeah that's correct, good job

Answer 20

:) i learned it from @substitute lol

Answer 21

haha well what a great teacher you had :P

Answer 22

ok last one i need help with please | What value of p solves the equation?
p^-5 = 1/243

Answer 23

ok so on the 'p' side of the equation, you want to invert it so you get 1/p^5 = 1/243. Do you see how then p^5=243? well then you just take the \[\sqrt[5]{243}\] and that's just 3

Answer 24

ok i got another one like that its | 3^n = 1/81 and i got 27 , is that correct ?

Answer 25

not quite

Answer 26

you need to convert 1/81 to a power of three so the indexes of the expressions on either side of the equations are equal

Answer 27

1/81=1/3^4=3^-4 therefore if 3^n=3^-4 then n=-4

Answer 28

ooh , god darn you good , Thank so much that was all the problems i needed help with | Go @substitute :")

Answer 29

i think you might be better at math and explaning then my current math teacher lol

Answer 30

haha no problem :) that wouldn't be a first, math teachers can sometimes be horrible

Answer 31

yes ,especially in georgia where i live

Answer 32

Hey i will have some more problems probably for you tomorrow because its 6:05am where i am and i havent been to sleep all day and im getting off os cya