if 3x=7y=10 and xy= -1 , find the value of 9x²+49y²..................thanks
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Answered by
7
3x - 7y) = 10
squaring both sides, we get
(3x -7y)2 = 100
⇒ 9x2 + 49y2 - 42xy = 100
⇒ 9x2 + 49y2 - 42 (-1) = 100
⇒ 9x2 + 49y2 + 42 = 100
⇒ 9x2 + 49y2 = 100 - 42 = 58
squaring both sides, we get
(3x -7y)2 = 100
⇒ 9x2 + 49y2 - 42xy = 100
⇒ 9x2 + 49y2 - 42 (-1) = 100
⇒ 9x2 + 49y2 + 42 = 100
⇒ 9x2 + 49y2 = 100 - 42 = 58
Ramsam:
yes 58 us correct
I forget to multiply2
why u r doing 3x - 7y and we hv to find 9x2 + 42y2
because after that we will find 9x^2 and 42^y2
Answered by
3
hre is your answer and this is correct
Attachments:
both r incorrect
what is the answer then
answer is 142
wait
brother you are wrong only 58 is correct
you can also find other too
okh
thanks
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