Marcus finds that (3x^2-2y^2+5x)+(4x^2+12y^2-7x)=7x^2 -10y-2x. what error did marcus make?

(3x²-2y²+5x)+(4x²+12y²-7x)

This is all about combining like terms.

(7x²+10y²-2x) is what I got.

(7x-10y-2x) is what Marcus got.

Marcus didn't add the squared symbol for 10y and he added a negative sign for 10y. He did -10y but it is +10y² because -2y²+12y²=10y². So, his problem is that Marcus didn't add right.

Hope this helps.

If it does, I would appreciate a brainliest rank.

<3

He combined the terms –2y2 and 12y2 incorrectly.

c.

step-by-step explanation:

she should of added 9^2 and 12^2. that is because it is a^2+b^2=c^2. c^2 is the hypotenuse and should always be bigger than the other two numbers. which is why she should of added 9 squared and 12 squared together instead of 15 squared.