Question

if (2x+3) (5x-7)=10xsquare -kx-21,then the value of k is​

Answer 1

$(2x + 3)(5x - 7) = 10 {x}^{2} - kx - 21 \\ 10 {x}^{2} - 14x + 15x - 21 = 10 {x}^{2} - kx - 21 \\ x = - kx \\ 1 = - k \\ k = (- 1)$

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