question_answer 1)

Find the value of the following expressions, when \[x=-1:\] (i) \[2x-7\]                           (ii) \[-x+2\]                         (iii) \[{{x}^{2}}+2x+1\]                    (iv) \[2{{x}^{2}}-x-2\]

Answer:

                (i) \[2x-7=2(-1)-7=-2-7=-9\].                 (ii) \[-x+2=-(-1)+2=1+2=3\]                 (iii) \[{{x}^{2}}+2x+1={{(-1)}^{2}}+2(-1)+1=1-2+1\]                 \[=1+1-2=2-2=0.\]                 (iv) \[2{{x}^{2}}-x-2=2{{(-1)}^{2}}-(-1)-2\]                 \[=2+1-2=3-2=1.\]