Yi Cheng let go of his fingers.

This guy's favorability rose to 70 and he didn't move again.

The new goddess collapsed on the table with a paralyzed face.

"emmm......" Yi Cheng looked at her and turned her over with his hand.

The goddess is facing upwards and her eyes are rolling.

"Aren't you also some big lady in reality?" Yi Cheng asked considering Ziqi's condition.

"Uh......"

The goddess eased up and opened her eyes slightly.

"I don't have a mortal body yet, ahem, I'm who I am, I'm @#%*¥"

"What?"

"I'm @#%*¥"

The goddess fell silent halfway through.

"Fuck you, my real name can't be known to mortals, so the damn system silenced me."

“……”

Yi Cheng rolled his eyes in his heart.

It seems that this goddess is a bit of a middle two.

"Since you're the system's pet to me, oh no, goddess," Yi Cheng held his chin and thought quietly.

"Then I'll give you a name."

"It's rude, you know who I am...... Lulu ......"

The goddess was rubbed by Yi Cheng with a finger on the table.

"Okay."

The goddess sits cross-legged on the table, grasping the sole of one foot in each hand.

"For the sake of communication, I will first promise you to use the name you gave me as a code name for my walk in the mortal world."

A satisfied smile appeared on Yi Cheng's face.

He picked up the math book and began to flip through it.

Since she is the goddess of mathematics, it should be good to use beautiful mathematical language as a name, right?

"Gauss?"

It's not good, it's too disagreeable.

Nor can it be called Newton.

Fourier sounds like a girl's name.

Theorem?

The theorem, just listening to the pronunciation, seems to be quite cute.

The goddess looked at the evil smile on Yi Cheng's face, and couldn't help but feel a chill in her heart, and hugged her shoulders with both hands.

Formula?

Yi Cheng frowned.

It's so hard, it's so hard, it's so hard to choose a name than to do a math problem.

emmmm……

Formula, difficult?

It's hard to think about, but that sounds pretty good.

I'm such a genius.

A little more polishing to make it look like a girl's name-

"Okay, that's it."

Yi Cheng clenched his fist and smashed it into his hand.

"W-what......?" The goddess's voice trembled slightly.

When she encounters such a host, she is considered to have fallen into blood mold.

"I'll call you Gong Sinan."

"Huh?"

The goddess blinked her big eyes.

I didn't expect the name to land in the end is quite good.

After confirming that the name of the goddess in the system had officially changed to Gong Sinan, Yi Cheng smiled contentedly.

"Okay."

He pushed away his chair and stood up, then pulled out a small piece of clothing from a drawer.

Well......

This Asuna dress is Ziqi's, and there is still her fragrance on it.

Although she will never wear it again, she will not be able to wear it......

Let's collect it first.

Yi Cheng handed another Rem T-shirt to Gong Sinan.

"You wear this dress first, and your pants."

He proceeded to hand her Rem's Harmony Short, Flush Pants.

The Little Mermaid doesn't need it, but this guy has a pair of human legs.

Gong Sinan blinked his eyes and looked at him blankly.

After a pause for a few seconds, she chose to put her clothes on.

To be honest, when she puts on the T-shirt, she still looks a little playful and cute.

"Is your hair a little too long?"

Yi Cheng looked at her suspiciously.

The goddess's hair hangs down to her ankles, and it looks like a tree from behind.

"The rain girl has no melons."

She quickly took a step back and nervously held her long hair.

"Okay, as long as you don't feel hot."

Yi Cheng took out the remaining Dream Fruit from his backpack and handed it to Si Nan.

"Eat some today, grow up quickly, and I'll make you fish tomorrow."

"Huh?"

Gong Sinan blinked his big eyes, is this guy a fine man?

It was so violent just now, and now it's so good to me?

No, you can't succumb to the enemy's sugar-coated shells.

I won't eat the food that comes from the spur when I am killed.

The goddess puffed up her chin.

However, after smelling the scent of the dream fruit, he gave up his resistance.

Gong Sinan sat on the table with the dream fruit in his arms and took a big bite.

"Well, it smells so good."

……

Very good, the favorability has increased by two points.

Yi Cheng nodded and left his chair

The goddess looked up and watched blankly as he lay down on the bed.

No time can be wasted.

Now that the dream system can continue to work again, it must be cherished.

Yi Cheng closed his eyes and prepared to enter the dream.

Just half-asleep, a tender body crawled into his chest.

"! What are you doing!? ”

Yi Cheng was startled by the pet god who suddenly crawled on his body.

"I'm low in temperature, I'm going to die if I leave the host."

The goddess pressed her ear to his chest.

“…… Are you cold-blooded? ”

……

After three minutes, Yi Cheng fell asleep.

The goddess also fell asleep.

【In Dream】

Yi Cheng sat up from the bed, carefully placed the goddess beside her, and covered her with a quilt thoughtfully.

The goddess has four paws facing the sky, and the sleeping position used is a mixed recumbent position.

He sat down at his desk and turned on the lamp.

With the bonus of math skills, he felt refreshed and in a good state, which was very suitable for learning.

He turned on his phone and connected to Yan Ziqi's video.

"Hey, it's punctual."

Ziqi was wearing a pajamas, as if she had just taken a shower, and her hair had not yet been completely dried.

They agreed to study together in the evening.

"You know what, I'm getting better at night."

She pulled the camera farther away, then stood up and lifted her clothes upwards.

You can see a little arc, which means that she has indeed just taken a shower.

The green scales on the waist and abdomen have decreased a lot, and the skin is much more normal now.

"Well, he's recovering well." Yi Cheng glanced at it lightly.

"Hmmm......"

Ziqi frowned, "It seems that you prefer me to be a fish......"

"No, I'd rather have you with me." Yi Cheng didn't raise his head, and took out the math problem from his school bag.

"......" Ziqi's face was a little hot.

She flipped through the pages and talked.

"What are you going to study tonight, by the way, what is the question that your math teacher gave today?"

Yi Cheng held up a note and held it close to his phone.

Ziqi stared for more than ten seconds.

"Oh, Lagrangian presolution."

The Lagrangian presolution is the law discovered by Lagrange when solving multiple unary equations.

Vedic theorem explains the relationship between roots and coefficients, and Lagrange goes one step further, taking inspiration from Vedic theorem and the permutation equation, and discovering that there are two very important laws for univariate equations of less than four degrees:

………

In a nutshell, the Lagrangian presolution can solve equations below the fifth degree.

This is something that high school students know.

At the same time, he was inspired by this to overcome five difficulties, but was met with strong resistance.

The fifth-order equation fails to solve the prefix in the same way.

Therefore, Lagrange believed that there is no general formula for finding roots for functions of more than five times.

But why is he great, and why is the Lagrangian presolution a very significant event in the history of mathematics?

Because from it, the prelude to group theory was opened, and an important branch of mathematics was created.

Ran Bingqing's problem for Yi Cheng was to ask him to prove that the equation with a Lagrangian presolution of less than 4 degrees is correct.

The two of them are in a wonderful state, and the more they prove, the happier they become.

Yi Cheng was halfway through the solution, and suddenly clutched his chest in pain.

"What's wrong?" Yan Ziqi's face changed greatly.

"Hmm...... Hmmm......"

Yi Cheng's mouth opened wide, his eyes widened, and he couldn't breathe.

With a thud, he collapsed from his chair.