ICSE Class 9 Answered

solve the following simultaneous linear equantion by substiution method : - 4x- 3y = 11 6x + 7y = 5

Asked by siddeshmankar90.9spicertl | 28 May, 2020, 03:16: PM

Expert Answer

4x- 3y = 11

→ x = $begin mathsize 16px style fraction numerator 11 plus space 3 straight y over denominator 4 end fraction end style$ .... (i)

6x + 7y = 5 .... (ii)

$begin mathsize 16px style Substitute space the space value space of space straight x space form space left parenthesis straight i right parenthesis space in space equation space left parenthesis ii right parenthesis comma space we space get 6 open parentheses fraction numerator 11 plus 3 straight y over denominator 4 end fraction close parentheses space plus space 7 straight y space equals space 5 rightwards double arrow space fraction numerator 66 space plus space 18 straight y space plus space 28 straight y over denominator 4 end fraction equals 5 rightwards double arrow 66 space plus space 46 straight y space equals space 20 rightwards double arrow straight y space equals space fraction numerator negative 46 over denominator 46 end fraction equals space minus 1 From space left parenthesis straight i right parenthesis comma space we space get straight x space equals fraction numerator 11 plus 3 left parenthesis negative 1 right parenthesis over denominator 4 end fraction equals fraction numerator 11 minus 3 over denominator 4 end fraction equals space 8 over 4 equals space 2 end style$