Question

19. If x + y = 9, x - y = -5 then 4 xy is
a. 65
b. 45
c. 56
c. 35

Answer 1

Step-by-step explanation:

x+y =9 eq1

x-y = -5 eq2

eq1 + eq2

2x = 4

x = 2

sub x=2 in eq1

2+y=9

y = 7

therefore 4xy = 4(2)(7)

= 56

therefore 4xy = 56

Answer 2

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Given:-

x + y = 9 ---------(1)

x - y = -5---------(2)

Now,

(1) +(2) => x + y + x - y = 9 -5

=> 2x = 4

=> x = 2

Putting the value of x in eqn(1) ,

2 + y = 9

=> y = 7

So,

• x -------> 2
• y --------> 7

Hence,

4xy

= 4. 2 . 7

= 56

$\colorbox{yellow}{Answer\:\:56}$