Question

6. If x + y = 17 and x - y = 15.
then the value of 16 xy (12 +
y?) is
(1) 16135
(2) 12
(3) 48
(4) 35 (17 +15)
(5) 36
​

Answer 1

x+y=17

x-y=15

by elimination method

adding both equation

(x+y)+(x-y)=17+15

2x=32

x=16

putting valie of x in x+y=18

16+y=17

y=17-16

y=1

putting value of x and y in 16xy(12+y)

=>16×16×1(12+1)

=>256(13)

=>3328

Answer 2

${\huge {\mathfrak {Answer :-}}}$

◾We have,

${} \implies x + y = 17.$

${} \implies x = 17 - y.$ ___________(1)

◾And,

${} \implies x - y = 15.$

${} \implies x = 15 + y.$ ___________(2)


✨$\bold {Method \:of\: Substitution}$ ✨


◾Substituting value from eq. (1) and putting it in eq. (2), we get

${} \implies 17 - y = 15 + y.$

${} \implies 2y = 17 - 15.$

${} \implies 2y = 2.$

${} \implies y = 2/2.$

${} \implies y = 1.$

◾Now,

Putting y = 1 in (2),

${} \implies x = y + 15.$

${} \implies x = 15 + 1.$

${} \implies x = 16.$

✨$<b>Hence, x = 16 and y = 1</b>$ ✨

◾Therefore,

${} = 16xy (12 + y)$

${} = 16 × 16 × 1 ( 12 + 1)$

${} = 256 × 13$

${} = 3328$

✨$<b>Hence, 3328 is the answer. </b>$ ✨