Question

v) 100a2 + 81b2 +49c2 - 180ab - 140ac + 126bc​

Answer 1

Answer:

we can write this as,

(-10a)² +(9b)² +(7c)² +2(-10a)(9b) +2(-10a)(7c)

+2(9b)(7c)

we know formula,

a²+b²+c²+2ab+2bc+2ca = (a+b+c)²

=> (-10a+9b+7c)²

Answer 2

$\mathtt{100a²+81b²+49c²-180ab-140ac} </p><p>\mathtt{+126bc}$

$\mathtt{= (-10a)²+(9b)²+(7c)²-2×(-10a)×9b}$

$\;\;\;\;\mathtt{+2×(-10a)×7c+2×9b×7c}$

$\mathtt{= (-10a+9b+7c)²}$

$\large \texttt{We have used the identity :}$

$\mathtt{(a+b+c)²=a²+b²+c²+2ab+2bc+2ac}$