\(G=\left(5x-7\right)\left(7x+3\right)-\left(7x+2\right)\left(5x-4\right)\)
\(=35x^2+15x-49x-21-35x^2+28x-10x+8\)
\(=-16x-13\)
Thay x = -3 \(\Rightarrow G=35\)
Vậy G = 35 khi x = -3
\(G=\left(5x-7\right)\left(7x+3\right)-\left(7x+2\right)\left(5x-4\right)\)
\(=\left(35x^2+15x-49x-21\right)-\left(35x^2-28x+10x-8\right)\)
\(=35x^2+15x-49x-21-35x^2+28x-10x+8\)
\(=-16x-13\)
Thay \(=-3\) vào biểu thức \(G\) , ta được :
\(G=-16x-13=-16\left(-3\right)-13=48-13=35\)
\(G=\left(5x-7\right)\left(7x+3\right)-\left(7x+2\right)\left(5x-4\right)\)
\(G=35x^2+15x-49x-21-\left(35x^2-28x+10x-8\right)\)
\(G=35x^2-34x-21-35x^2+18x+8\)
\(G=-16x-13\)(1)
Thay \(x=-3\) vào (1) ta được:
\(-16.\left(-3\right)-13=48-13=35\)
Vậy..............
Chúc bạn hcọ tốt!!!
G= (5x-4 - 3)(7x + 3) -(5x - 4)(7x - 2)
G= (5x-4)(7x+3) -(5x-4)(7x-2) -3(7x+3)
G=(5x-4)(7x+3-7x+2) -3(7x+3)
Thay x=-3 vào, ta có:
G=(5*(-3)-4)*5-3(7*(-3)+3)
G=(-19)*5- 3*(-18)
G= -95+ 54
G= -41
