Add the following like terms. (i) 12ab, 9ab, ab(ii) 10x2, – 3x2, 5x

1.	Add the following like terms. (i) 12ab, 9ab, ab(ii) 10x2, – 3x2, 5x2(iii) – y2, 5y2, 8y2, – 14y2(iv) 10mn, 6mn, – 2mn, – 7mn
Answer» (i) Sum of 12ab, 9ab, ab = 12ab + 9ab + ab = (12 + 9 + 1) ab = 22 ab. (ii) Sum of 10x², – 3x², 5x² = 10x² + (- 3x² ) + 5x² = 10x² – 3x² + 5x² = (10 – 3 + 5) x² = 12x² (iii) Sum of – y², 5y², 8y², – 14y² = – y² + 5y² + 8y² + (- 14y²) = – 1y² + 5y² + 8y² – 14y² = (- 1 + 5 + 8 – 14) y² = – 2y² (iv) Sum of 10mn, 6mn, – 2mn, – 7mn = 10mn + 6mn + (- 2mn) + (- 7mn) = 10mn + 6mn – 2mn – 7mn = (10 + 6 – 2 – 7) mn = 7mn

Add the following like terms. (i) 12ab, 9ab, ab(ii) 10x2, – 3x2, 5x2(iii) – y2, 5y2, 8y2, – 14y2(iv) 10mn, 6mn, – 2mn, – 7mn

Answer»

(i) Sum of 12ab, 9ab, ab

= 12ab + 9ab + ab

= (12 + 9 + 1) ab

= 22 ab.

(ii) Sum of 10x², – 3x², 5x²

= 10x² + (- 3x² ) + 5x²

= 10x² – 3x² + 5x²

= (10 – 3 + 5) x²

= 12x²

(iii) Sum of – y², 5y², 8y², – 14y²

= – y² + 5y² + 8y² + (- 14y²)

= – 1y² + 5y² + 8y² – 14y²

= (- 1 + 5 + 8 – 14) y²

= – 2y²

(iv) Sum of 10mn, 6mn, – 2mn, – 7mn

= 10mn + 6mn + (- 2mn) + (- 7mn)

= 10mn + 6mn – 2mn – 7mn

= (10 + 6 – 2 – 7) mn

= 7mn