if 7x-4y=9 and xy=3 then find the value of ( 7x+4y)²
Answers
Answered by
2
on squaring we get 49x^2+16y^2-56xy=81
now adding both sides 112xy we get
(7x+4y)^2=81+112xy
=81+336
417
now adding both sides 112xy we get
(7x+4y)^2=81+112xy
=81+336
417
Answered by
7
(7x-4y)=9
squaring both sides
49x²+16y²-56xy=81
add and subtract 56xy
49x²+16y²+56xy-112xy=81
(7x+4y)²=81+112xy
(7x+4y)²=81+336
(7x+4y)²=417
squaring both sides
49x²+16y²-56xy=81
add and subtract 56xy
49x²+16y²+56xy-112xy=81
(7x+4y)²=81+112xy
(7x+4y)²=81+336
(7x+4y)²=417
Similar questions