Question

7. If 3x + 4y = 7 and xy = 2, then find the value of 9x^2+ 16y^2
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Answer 1

Answer:

25

Step-by-step explanation:

$3x + 4y = 7$

and

$xy = 2$

so

${9x}^{2} + {16y}^{2}$

=????

$9( {1}^{2} ) + 16( {1}^{2} )$

$9 + 16$

$= 25 \: ans \:$

not sure about answer and hope it will be correct ...............

Answer 2

$\huge\underline\pink{AnsWeR}$

GIVEN-:

$3x+4y=7$

$xy=2$

FIND-:

$9x^2+16y^2=?$

SOLUTION-:

$Using-:(a+b)^2=a^2+b^2+2ab$

$(3x+4y)^2=(7)^2$

NOW,

$(3x+4y)^2=(3x)^2+(4y)^2+2(3x×4y)$

By putting values

$(7)^2=(3x)^2+(4y)^2+2(12xy)$

$49=9x^2+16y^2+24xy$

$49=9x^2+16y^2+24×2$

$49=9x^2+16y^2+48$

$49-48=9x^2+16y^2$

$1=9x^2+16y^2$

ANSWER

$1=9x^2+16y^2$