Solution : Let us consider basis for R2 given by:S={[−21],[13]} and let us consider linear operator T:R2→R3 for which:T(v1)=⎣⎡−140⎦⎤ and T(v2)=⎣⎡0−59⎦⎤Let us first find formula for T(x1,x2):(x1,x2)=av1+bv2 =a[−21]+b[13][x1x2]=[−2(a)1(a)]+[1(b)3(b)][x1x2]=[−2aa]+[b3b][x1x2]=[−2a+ba+3b]⇒ x1=−2a+b and x2=a+3b,Solving these equations for a and b,we geta=71(−3x1+x2) and b=71(x1+2x2) which gives us:(x1,x2)=av1+bv2=71(−3x1+x2)v1+71(x1+2x2)v2Therefore,we have:T(x1,x2)=T(av1+bv2)=aT(v1)+bT(v2) =71(−3x1+x2)T(v1)+71(x1+2x2)T(v2) =71(−3x1+x2)⎣⎡−140⎦⎤+71(x1+2x2)⎣⎡0−59⎦⎤ =71 {(−3x1+x2)⎣⎡−140⎦⎤+(x1+2x2)⎣⎡0−59⎦⎤} =71{⎣⎡3x1−x2−12x1+4x20⎦⎤+⎣⎡0−5x1−10x29x1+18x2⎦⎤} =71⎣⎡3x1−x2−17x1−6x29x1+18x2⎦⎤Which gives:T(4,−5)=71⎣⎡3(4)−(−5)−17(4)−6(−5)9(4)+18(−5)⎦⎤ =71⎣⎡12+5−68+3036−90⎦⎤ =71⎣⎡17−38−54⎦⎤ =⎣⎡717−738−754⎦⎤ =⎣⎡2.428571−5.428571−7.71428571⎦⎤
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