If (9x − 4)(9x + 4) = ax2 − b, what is the value of a?

The value of a is _____________.

Question

If (9x − 4)(9x + 4) = ax2 − b, what is the value of a?

The value of a is _____________.

anonymous · Answer

@jim_thompson5910

jim_thompson5910 · Answer

hint:

(x-y)*(x+y) = x^2 - y^2

anonymous · Answer

i stoll dont get it im lost as to how u solve these

jim_thompson5910 · Answer

has your teacher covered the difference of squares rule in any of the lessons?

anonymous · Answer

im taking an online course so the only explanation for problems we have are written down lessons and it hard for me to learn tht way

jim_thompson5910 · Answer

anonymous · Answer

ok

anonymous · Answer

not really but if u exokain to me i should pick up quickly

anonymous · Answer

*explain

jim_thompson5910 · Answer

have you learned of the FOIL rule at all?

anonymous · Answer

o ok yes

jim_thompson5910 · Answer

so you will FOIL out (9x-4)*(9x+4)

anonymous · Answer

u multiply the first outside then inner then last

jim_thompson5910 · Answer

yes

jim_thompson5910 · Answer

what do you get when you FOIL ?

anonymous · Answer

well wen i did the first terms i got 81 wich feels wrong to me

jim_thompson5910 · Answer

it's close, it should be 81x^2

jim_thompson5910 · Answer

notice how ax^2 and 81x^2 match up

anonymous · Answer

o ok i know it was x^2 but i was unsure about the 81 part

jim_thompson5910 · Answer

ah ok

anonymous · Answer

my bad my mom called me but b1x^2+36x-36x+16?

jim_thompson5910 · Answer

you mean 81x^2 + 36x - 36x + 16 right?

anonymous · Answer

yes lol my bad

jim_thompson5910 · Answer

what happens with the 36x and the -36x ?

jim_thompson5910 · Answer

they combine to what?

anonymous · Answer

cancell out of the equation leaving u with81x^2+16

jim_thompson5910 · Answer

oh my bad, the +16 should be -16

jim_thompson5910 · Answer

but yes they cancel

jim_thompson5910 · Answer

you should get 81x^2 - 16

anonymous · Answer

o yea becuse its a negative four time positive 4

anonymous · Answer

o ok thenw ats next

jim_thompson5910 · Answer

compare ax^2 - b with 81x^2 - 16

anonymous · Answer

so its 81?

jim_thompson5910 · Answer

a = 81, yes

anonymous · Answer

can u help with more?

jim_thompson5910 · Answer

sure, one more

anonymous · Answer

ok thank you

jim_thompson5910 · Answer

np

anonymous · Answer

Choose the correct simplification of 8x2(4x + 2x2 − 1).

jim_thompson5910 · Answer

when you distributed, what did you get?

anonymous · Answer

WHEN I DISTRIBUTE WAT DO I DO WITH THE ^2 THATS ON THE 8

jim_thompson5910 · Answer

you basically multiply 8x^2 by each term inside

jim_thompson5910 · Answer

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