SSC (English Medium) Class 8Maharashtra State Board
Share

# Simplify. (7a − 6b + 5c)2 + (7a + 6b − 5c)2 - SSC (English Medium) Class 8 - Mathematics

ConceptExpansion of (A + B + C)2

#### Question

Simplify.

(7a − 6b + 5c)+ (7a + 6b − 5c)2

#### Solution

It is known that,

$\left( a + b + c \right)^2 = a^2 + b^2 + c^2 + 2ab + 2bc + 2ca$

$\ \left( 7a - 6b + 5c \right)^2 + \left( 7a + 6b - 5c \right)^2$

$= \left( 7a \right)^2 + \left( - 6b \right)^2 + \left( 5c \right)^2 + 2 \times 7a \times \left( - 6b \right) + 2 \times \left( - 6b \right) \times 5c + 2 \times 5c \times 7a + \left( 7a \right)^2 + \left( 6b \right)^2 + \left( - 5c \right)^2 + 2 \times 7a \times 6b + 2 \times 6b \times \left( - 5c \right) + 2 \times \left( - 5c \right) \times 7a$

$= 49 a^2 + 36 b^2 + 25 c^2 - 84ab - 60bc + 70ca + 49 a^2 + 36 b^2 + 25 c^2 + 84ab - 60bc - 70ca$

$= 98 a^2 + 72 b^2 + 50 c^2 - 120bc$

Is there an error in this question or solution?

#### APPEARS IN

Balbharati Solution for Balbharati Class 8 Mathematics (2019 to Current)
Chapter 5: Expansion formulae
Practice Set 5.4 | Q: 2.3 | Page no. 28
Solution Simplify. (7a − 6b + 5c)2 + (7a + 6b − 5c)2 Concept: Expansion of (A + B + C)2.
S