Telangana SCERT Solution Class VIII (8) Math Chapter 12 Factorisation Exercise 12.4
Find the errors and correct the following mathematical sentences:
(i) 3(x – 9) = 3x – 9
(ii) x (3x + 2) = 3x2 + 2
(iii) 2x + 3x = 5x2
(iv) 2x + x + 3x = sx
(v) 4p + 3p + 2p + p – 9p = 0
(vi) 3x+2y = 6xy
(vii) (3x)2 + 4x + 7 = 3x2 + 4x + 7
(viii) (2x)2 + 5x = 4x + 5x = 9x
(ix) (2a + 3)2 = 2a2 + 6a + 9
(x) Substitute x = -3 in
(a) x2 + 7x + 12 = (-3)2 + 7 (-3) + 12 = 9 + 4 + 12 = 25
(b) x2 – 5x + 6 = (-3)2 – 5 (-3) + 6 = 9 – 15 + 6 = 0
(c) x2 + 5x = (-3)2 + 5 (-3) + 6 = -9 – 15 = -24
(xi) (x – 4)2 = x2 – 16
(xii) (x + 7)2 = x2 + 49
(xiii) (3a + 4b) (a – b) = 3a2 – 4a2
(xiv) (x + 4) (x + 2) = x2 + 8
(xv) (x – 4) (x – 2) = x2 – 8
(xvi) 5x3 ÷ 5x3 = 0
(xvii) 2x3 + 1 ÷ 2x3 = 1
(xviii) 3x + 2 ÷ 3x = 2/3x
(xix) 3x + 5 ÷ 3 = 5
(xx) 4x+3/3 = x + 1