The Total solution for NCERT class 6-12
(a) p(p – q) + q(q – r) + r(r – p)= (p × p) – (p × q) + (q × q) – (q × r) + (r × r) – (r × p)= p2 –pq + q2 –qr + r2 –rp= p2 +q2 +r2 –pq – qr – rp(b) 2x(z – x – y) + 2y(z – y – x)= (2x × z) – (2x × x) – (2x × y) + (2y × z) – (2y × y) – (2y × x)= 2xz – 2x2 –2xy + 2yz – 2y2 –2xy= -2x2 –2y2 +2xz + 2yz – 4xy= -2x2 –2y2 –4xy + 2yz + 2xz(c) 4l(10n – 3m + 2l) – 3l(l – 4m + 5n)= (4l × 10n) – (4l × 3m) + (4l × 2l) – (3l × l) – (3l × -4m) – (3l × 5n)= 40ln – 12lm + 8l2 –3l2 +12lm – 15ln= (40ln – 15ln) + (-12lm + 12lm) + (8l2 –3l2)= 25ln + 0 + 5l2= 25ln + 5l2= 5l2 +25ln(d) [4c(-a + b + c)] – [3a(a + b + c) – 2b(a – b + c)]= (-4ac + 4bc + 4c2) – (3a2 +3ab + 3ac – 2ab + 2b2 –2bc)= -4ac + 4bc + 4c2 –3a2 –3ab – 3ac + 2ab – 2b2 +2bc= -3a2 –2b2 +4c2 –ab + 6bc – 7ac