GATE 2020 MA – Question 59
A linear map T:R⁴→R[x] satisfies $T(-1,1,1,1)=x^2+2x^4$, $T(1,2,3,4)=1-x^2$ and $T(2,-1,-1,0)=x^3-x^4$. Find the coefficient of x⁴ in T(−3,5,6,6).
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Correct answer: 5 to 5
Explanation
The target vector is $2(-1,1,1,1)+(1,2,3,4)-(2,-1,-1,0)=(-3,5,6,6)$. By linearity its image is $2(x^2+2x^4)+(1-x^2)-(x^3-x^4)=1+x^2-x^3+5x^4$. The requested coefficient is 5.